Microsoft RAMCard C 97200 User Manual

RAMCard™  
A Peripheral for the Apple II®  
Produced by Microsoft  
Microsoft Consumer Products  
A division of Microsoft, Inc.  
10700 Northup Way  
C-97200  
Bellevue, WA 98004  
Copyright Notice  
This manual Copyrights Microsoft, 1980  
All Rights Reserved  
Printed in U.S.A.  
If you have any questions about this copyright, please contact:  
Microsoft Consumer Products  
A division of Microsoft, Inc.  
10700 Northup Way  
C-97200  
Bellevue, WA 98004  
RAMCard is a trademark of Microsoft.  
Apple is a registered trademark of Apple Computer Inc.  
Z-80 is a registered trademark of Zilug, Inc.  
Designer  
RAMCard was designed for Microsoft Consumer Products by Don Burtis of  
Burtronix, Villa Park, California. Microsoft Consumer Products is grateful to  
Burtronix for its contribution to making RAMCard a reality.  
2
TABLE OF CONTENTS  
Important Note for DOS 3.2  
CP/M Users  
8
9
CHAPTER 2 INSTALLATION INSTRUCTIONS  
Opening your Apple II  
Inserting the Plug  
9
13  
CHAPTER 3 USING RAMCard  
17  
Existing Software  
Some Compatible Packages  
17  
19  
22  
25  
Control Addresses  
Additional Technical Details  
3
 
Registration Information  
Please take a moment now to fill out the RAMCard registration  
card that is enclosed and return it to us. We must have your  
registration card on file in order to contact you regarding any changes  
or updates to this product. Failure to return the registration card does  
not void your warranty, hut will make it impossible for us to contact  
you.  
RAMCard Warranty  
Microsoft Consumer Products (“MCP”) warrants to the original user  
of this product that it shall be free of defects resulting from faulty  
manufacture of the product or its components for a period of ninety  
(90) days from the date of sale. Defects covered by this Warranty shall  
be corrected either by repair or, at MCP’s election, by replacement. In  
the event of replacement, the replacement unit will be warranted for  
the remainder of the original ninety (90) day period or 30 days, which-  
ever is longer.  
If this product should require service, return it to Microsoft Consumer  
Products, 400 108th Ave. NE, Suite 200, Bellevue, Washington 98004,  
postage paid, along with an explanation of the suspected defect. MCP  
will promptly handle all warranty claims.  
THERE ARE NO WARRANTIES, EXPRESS OR IMPLIED, IN-  
CLUDING BUT NOT LIMITED TO THOSE OF MERCHANTA-  
BILITY OR FITNESS FOR A PARTICULAR PURPOSE, WHICH  
EXTEND BEYOND THE DESCRIPTION AND DURATION SET  
FORTH HEREIN.  
MCPs SOLE OBLIGATION UNDER THIS WARRANTY IS  
LIMITED TO THE REPAIR OR REPLACEMENT OF A DEFEC-  
TIVE PRODUCT AND MCP SHALL NOT, IN ANY EVENT, BE  
LIABLE FOR ANY INCIDENTAL OR CONSEQUENTIAL DAM-  
AGES OF ANY KIND RESULTING FROM USE OR POSSESSION  
OF THIS PRODUCT.  
Some states do not allow 1) limitations on how long an implied warran-  
ty lasts, or 2) the exclusion or limitation of incidental or consequential  
damages, so the above limitations or exclusions may not apply to you.  
This Warranty gives you specific legal rights, and you may also have  
other rights which vary from state to state.  
4
 
Service Information  
If your RAMCard requires repair, please return it to the dealer from  
whom it was purchased. If it is not possible to return the RAMCard to  
your dealer, you may send it directly to Microsoft Consumer Products.  
If the repair is required during the warranty period, please enclose  
proof of purchase. During warranty, we will replace or repair your  
RAMCard without charge. See previous section for more details re-  
garding warranty coverage.  
If the RAMCard requires service after the warranty period expires, it  
will be repaired for a flat fee of $39.50. This service charge does not  
cover damage due to negligence, misuse, or inadequate packaging on  
return to MCP.  
To return your RAMCard for service, please mail it post-paid to Micro-  
soft Consumer Products. Package the card securely as we cannot be  
responsible for damage due to shipping. BE SURE to enclose proof of  
purchase for warranty work or a check or money order for $39.50 for  
non-warranty repairs.  
Mail post-paid to:  
Microsoft Consumer Products  
A division of Microsoft, Inc.  
10700 Northup Way  
C-97200  
Bellevue, WA 98004  
5
 
6
CHAPTER 1  
INTRODUCTION  
RAMCard is a printed circuit board that contains 16K bytes of addi-  
tional random-access memory (RAM) for your Apple II or Apple II  
Plus computer.  
RAMCard is designed for an Apple II with 48K bytes of RAM already  
in place. If your Apple II has less than 48K RAM, you will need to  
purchase enough 16K memory modules to bring your Apple II up to  
48K.  
RAMCard is compatible with Microsoft Consumer Products SoftCard,  
a circuit card for the Apple which contains a Z80 microprocessor, and  
allows you to run the CP/M operating system. RAMCard and Soft-  
Card together make a powerful combination that turns your Apple II into  
a full memory (56K), flexible (two microprocessors) microcomputer.  
With RAMCard and SoftCard in place, you have 56K RAM available  
to run any of the languages available for the SoftCard, including  
Microsoft’s BASIC-80 (included in the SoftCard package), COBOL-80,  
FORTRAN-80, BASIC Compiler, and Assembly Language Develop-  
ment System.  
RAMCard contains 16K of memory. But, because only 12K of addi-  
tional addressing space is available in the Apple, 4K of addressing space  
must be shared by two 4K memory banks. This means that only 12K of  
RAMCard RAM is available to you at a given time.  
7
 
IMPORTANT NOTE FOR DOS 3.2 USERS  
AND FOR 13-SECTOR CP/M USERS  
Apple II computers come standard with one of two BASICs: Applesoft  
or Integer BASIC. Standard Apple II systems have Integer BASIC and  
Apple II Plus systems have Applesoft.  
If you are using an Apple Firmware Card installed in Slot 0 to make  
available the other version of BASIC, you must remove it when RAM-  
Card is installed. This means that the BASIC on the Apple Firmware  
Card will no longer be available.  
To use RAMCard with the Microsoft SoftCard and CP/M, you must  
have a 16-sector system. This is because you must use the CPM56  
program to update your CP/M system to 56K. The CPM56 utility is  
included only on your 16-sector CP/M master disk. In addition, most of  
the other software available for RAMCard also requires a 16-sector  
disk system.  
These problems can be solved with Apple Computer’s DOS 3.3 16-  
sector update kit, available at your dealer. This package contains soft-  
ware that will allow you to load the other version of BASIC into  
RAMCard, so that both versions of BASIC will be available for use by  
Apple DOS programs. A disk is also supplied with the DOS 3.3 package  
that will allow you to boot your old 13-sector disks.  
8
 
CHAPTER 2  
INSTALLATION  
INSTRUCTIONS  
This chapter gives step-by-step instructions for installing RAMCard.  
We recommend that you read all the instructions first to acquaint  
yourself with the overall procedure. Then, perform each step with care  
exactly as described.  
Opening Your Apple II  
Since RAMCard is to be installed inside your Apple II, you must  
remove the cover of your Apple before you start.  
CAUTION  
\
It is dangerous to open any electrical or electronic  
device with the power turned on. Additionally, at-  
tempting to insert or remove peripheral cards while  
your Apple’s power is on will probably destroy the  
cards and other parts of your APple II. Be sure to  
turn off the power to your Apple II before perform-  
ing any of the steps in this procedure.  
1 . Turn off the power.  
The POWER light on the lower left corner of the keyboard should  
not be illuminated.  
9
 
2 . Remove the cover from your Apple II.  
Pull up on the rear edge of the cover until the fasteners at the rear  
corners pop apart. Do this only firmly enough to separate the fas-  
teners, then stop. Do not pull up any further.  
3 . Slide the cover backward.  
Slide the cover away from the keyboard towards the rear of your  
Apple II. The interior of your Apple II should now be exposed.  
Removing A Chip  
Before you can install RAMCard, you must remove one of the RAM  
chips inside your Apple II. Later, you will insert the plug on the RAM-  
Card connector cable into the space where the chip is now.  
1 . Look into your Apple II.  
Familiarize yourself with the inside.  
power supply cover  
edge connector slot  
memory chip to be removed  
RAM chips located  
in this square  
The Interior of an Apple II  
10  
 
You should see:  
A big silver- or gold-colored box (the power supply cover) along  
the left side.  
Eight long, narrow slots (edge-connector receptacles), green or  
black outside with gold-plated contacts inside, located perpen-  
dicular to and against the back wall of the Apple II enclosure.  
The slots are numbered from left to right, from 0 to 7. The  
numbers are located between the far end of the slots and the back  
wall.  
A 4 inch by 4 inch square outlined in white, located directly  
behind the keyboard (RAM chips are located here).  
2 . Touch the power supply cover.  
Touch the cover to discharge any static electricity you may be  
carrying.  
3 . Find Slot 0.  
Lean over your Apple II to see the numbers at the far end (back wall  
side) of the eight slots. They are numbered from left to right,from 0  
to 7. You want the number 0 slot, the leftmost.  
4 . Remove card from sLot 0.  
If there is a card in Slot 0, it must be removed since Slot 0 is the slot  
you will use for RAMCard. If there is no card in Slot 0, disregard this  
step and go on to step 5.  
5 . Find the left rear memory chip.  
Look inside the white square. There are three rows of eight memory  
chips installed within the square. Locate the chip in the last row  
(farthest from the keyboard) and the first column (farthest left,  
closest to the power-supply cover). This is the chip you will need to  
remove.  
6 . Remove the left rear memory chip.  
1 1  
Removing the Chip  
REMEMBER: Touch the power-supply cover to discharge static  
electricity on your body before grasping the chip.  
WARNING  
Remove the memory chip carefully. Be sure you do  
not damage the chip or the circuit board sockets in  
any way. Avoid touching the pins on the chip with  
your fingers because static electricity on your body  
may damage the chip. Grasp the chip by the ends  
and with the chip extractor only.  
Use the chip extractor (which resembles a large pair of tweezers)  
included in the RAMCard package to grasp the chip at each end.  
There is a slot under the chip at each end where the extractor prongs  
will fit. Wiggle the chip very slightly to loosen it. Apply no more  
1 2  
upward or lateral force than necessary to remove the chip gently so  
that the chip will not be damaged.  
Inserting RAMCard  
Inserting RAMCard is actually two separate procedures. First, you  
insert the plug at the end of the connector cable into the socket left  
empty when you removed the chip. Then, insert the card itself into Slot  
0
Inserting The Plug  
1.Examine RAMCard.  
Set the card in front of you, face up.  
edge connector  
connector cable  
RAMCard  
1 3  
 
Notice the connector cable at the bottom left corner of this card. At  
the end of the cable is a plug. Notice that RAMCard also has an I/O  
connector strip along one edge. The cable plug will go into the  
vacant memory chip space inside your Apple II. The edge-connector  
will go into Slot 0.  
2.Position the card and plug.  
Hold the card on edge over the Apple II so that the cable end is  
toward the keyboard, the side with the chips is facing to your right,  
and the edge-connector is positioned over Slot 0.  
3.Insert the plug.  
Inserting the RAMCard Cable  
Position the pins on the cable plug directly over the holes where the  
memory chip was removed. Gently apply pressure to the top of the  
plug. Apply only enough pressure to seat the plug completely.  
1 4  
If the plug does not slide into the holes easily, remove it, reposition  
the pins, then app]y gentle pressure until the plug is seated. A very  
slight wiggle may be used to help seat the plug. But, any lateral  
movement may damage a pin so avoid wiggling if you can. If you  
must wiggle the plug to seat it fully, be sure the pins are lined up  
properly first, then wiggle only very slightly and very slowly.  
Inserting RAMCard  
1.Position RAMCard over Slot 0.  
Hold RAMCard so that it can be inserted in Slot 0 without twisting  
the cable. If RAMCard cannot be inserted without twisting the  
connector cable, the plug was inserted backwards. Remove the plug  
and reinsert it So that the connector cable will not be twisted when  
RAMCard is inserted.  
2.Position the edge-connector into Slot 0.  
Inserting RAMCard into Slot 0  
15  
 
Set the connector strip on the bottom edge of RAMCard into Slot 0.  
Be sure that the connector on the card is centered in the slot.  
3. Press RAMCard into place.  
Do not wiggle RAMCard from side to side! If necessary, you can  
wiggle the card lengthwise, from back to front to back, to help seat  
the card into Slot 0 completely.  
4. Recheck seating of plug and card.  
Be sure that both the plug and the card are fully seated.  
5. Replace cover.  
When you are satisfied that the plug and card are correctly placed  
and installed (you may want to reread the instructions), slide the  
cover of your Apple II forward to the keyboard. When the cover is in  
place, press down on the rear corners of the cover until the fasteners  
snap closed.  
6. Power up.  
Your Apple II is now ready to run. You can switch on the power and  
bring up CP/M if you have the SoftCard. With the SoftCard in-  
stalled, you now have 56K contiguous RAM available to run 56K  
CP/M. You can create 56K CP/M system disks with the CPM56  
utility included with your SoftCard package. For instructions on  
using SoftCard and RAMCard together, refer to the SoftCard Man-  
ual, Using Apple CP/M with the Apple Language Card, page 1-13.  
For each reference to the Apple Language Card, simply substitute  
RAMCard.  
Other software can also be used with RAMCard. See Chapter 3 for  
more information.  
1 6  
CHAPTER 3  
USING RAMCard  
For some Apple II configurations, installing RAMCard will change the  
procedures you use to run your existing software.  
This chapter outlines which configurations of the Apple II are affected  
by installing RAMCard and what software procedures you need to  
change. This chapter also Lists some of the software that is compatible  
with RAMCard.  
How To Use Your Existing Software  
Installing RAMCard in your Apple II will affect the operation of your  
existing software if:  
1. You are using an Apple Firmware Card in Slot 0.  
2. You are using 13-sector disks with SoftCard and CP/M  
Let’s discuss these two topics in more detail.  
1. Apple II computers come standard with one of the two BASICs:  
Applesoft or Integer BASIC. Standard Apple II systems have Inte-  
ger BASIC, and Apple II Plus systems have Applesoft.  
If you are using an Apple Firmware Card installed in Slot 0 to make  
available the other version of BASIC, you must remove it when  
1 7  
 
RAMCard is installed. This means that the BASIC on the Apple  
Firmware Card will no longer be available. When you lose the  
BASIC on the Firmware Card, you also lose access to any programs  
you may have that are written in that BASIC.  
2. If you are using CP/M (and SoftCard), then you must use the  
CPM56 utility to take advantage of RAMCard’s extra memory. The  
CPM56 utility is found only on the 16-sector CP/M master in the  
SoftCard package.  
Refer to the Microsoft SoftCard Manual, Using Apple CP/M with  
the Apple Language Card,” page 1-13, for instructions for using the  
CPM56 utility.  
Most of the other software that takes advantage of RAMCard, such  
as Apple FORTRAN, is supplied on 16-sector disks only. To run this  
software, you will need a 16-sector disk system. One exception is  
VisiCalc, which does not require a 16-sector disk system to take  
advantage of the extra RAMCard memory.  
If you are using a 13-sector system, and you want to use some of the  
software that comes only on 16-sector disks, you must update to a  
16-sector system.  
Solution  
The solution to these problems is to update your system to Apple DOS  
3.3. Then, you will have both BASICs on diskette, you can load the  
“other” BASIC into RAMCard, and you will again have access to the  
programs you wrote in the BASIC on your Firmware Card. Updating  
to Apple DOS 3.3 also allows you to boot 13-sector diskettes, and  
allows you to use 16-sector CP/M (and hence CPM56).  
Compatible Software  
RAMCard is compatible with all the software that can be used with  
the Apple Language Card. In fact, RAMCard operates identically to  
the Language Card, with one exception: RAMCard does not have  
Autostart ROM. See more on Autostart ROM below.  
1 8  
 
Some of the software packages that can be used with RAMCard are:  
CP/M, which also allows you to use:  
Microsoft’s COBOL-80  
Microsoft’s FORTRAN-SO  
Microsoft’s BASIC Compiler  
Microsoft’s Assembly Language Development System  
Applesoft BASIC  
Integer BASIC  
VisiCalc  
Apple Pascal system Apple FORTRAN  
Apple PILOT  
Since RAMCard operates identically to the Apple Language Card, you  
need only refer to the instructions in the software product documenta-  
tion for using that software with the Apple Language Card; the operat-  
ing instructions for use with RAMCard are exactly the same.  
Autostart ROM  
RAMCard does not include Autostart ROM. In a few cases, lack of  
Autostart ROM may affect use of software designed to be used with the  
Apple Language Card.  
In addition, unless your Apple II has Autostart ROM installed on-  
board, the convenient auto-boot features of Autostart ROM are not  
available. In order to behave exactly as if a Language Card is installed,  
some software may require Autostart ROM.  
If you have an Apple II Plus, your computer has Autostart ROM  
installed on-board. If you have an Apple II, you may want to install  
Autostart ROM to take advantage of the auto-boot features.  
19  
 
20  
CHAPTER 4  
ADDRESSING RAMCard  
The information in this chapter is highly technical and is intended as  
reference material only.  
This chapter describes the addressing of RAMCard. Memory maps  
showing the addresses used for RAMCard RAM and Apple on-board  
ROM and a description of the control addresses and their functions  
make up most of the information. At the end of the chapter, some  
additional technical details relating to RAMCard and Apple II hard-  
ware are described.  
RAMCard contains 16K of memory. But, because the memory  
addresses $C000 through $CFFF are used for the Apple’s I/O, only the  
12K of space from $D000 to $FFFF is available to address the 16K of  
RAMCard. To address all of the 16K of memory on RAMCard, the  
lower 4K of RAMCard address space is used twice. The programmer  
can select either of two 4K memory banks to occupy the space from  
$D000 to $DFFF at one time.This allows 8K of memory to be accessed  
in only 4K of address space.  
Also, RAMCard shares this memory space with the on-board Apple  
ROMs. The programmer can, therefore, choose whether the memory  
addresses between $D000 and $FFFF will be used to read ROM or read  
RAMCard RAM, and whether these same addresses will be write-  
enabled or write-protected for RAMCard RAM. The selection of these  
functions plus the selection of which 4K memory bank will be used are  
performed by accesses to control addresses.  
2 1  
 
Because the address space $C000-$CFFF is used by the Apple,  
2 2  
Addressing information is divided into three sections in this chapter.  
The first section shows memory maps. The maps show the memory  
addresses for the functions called through control addresses. The sec-  
ond section describes these control addresses, which provide memory  
mode selection, RAM write-enable/-protect, and bank switching. The  
third section describes additional technical details about status bits,  
about the LED indicators on RAMCard, and about RAMCard hard-  
ware details.  
Memory Maps  
The following diagrams illustrate the range of addresses used for the  
memory functions of RAMCard and the Apple on-board ROM.  
FFFF  
RAMCard  
RAM  
Apple  
on-board  
ROM  
E000  
DFFF  
BANK 2  
BANK 1  
D000  
Control Addresses  
The control addresses are special memory addresses that, when ac-  
cessed, control simultaneously three unrelated functions:  
1. Select write-protect or write-enable RAMCard’s RAM  
2. Select RAMCard RAM read or Apple II on-board ROM  
3. Select which 4K bank will be mapped into the $D000-$DFFF  
addressing space.  
Because the address space $C000-$CFFF is used by the Apple.  
22  
 
only 12K ($D000-$FFFF) of address space is available for 16K  
RAM. Using the control addresses to switch between the two  
4K banks allows you to address 8K RAM with only 4K of  
address space.  
The remainder of the RAMCard RAM ($E000-$FFFF) is di-  
rectly addressable.  
Control addresses are entered either in hexadecimal, for assembly lan-  
guage programs, or in decimal, for BASIC programs. Hexadecimal  
addresses begin with the dollar sign ($).  
All of the hexadecimal control addresses have the form $C08x. x is any  
of the hexadecimal digits 0-3,8-9,A-B. The value of x determines the  
bank and which functions are selected. When the value of x is convert-  
ed to binary, then the functions associated with the bit positions can be  
seen more clearly.  
The hexadecimal digits 0-3,8-9,A-B convert to binary as follows:  
HEX  
BINARY  
0
1
2
3
0 0 00  
0 0 01  
0 0 10  
0 0 11  
8
9
A
B
1 0 00  
1 0 01  
1 0 10  
1 0 11  
Bits 0 and 1 (the two right columns of each binary number) are read  
together to select the functions. As you can see there are only four  
selections — 00, 01, 10, 11. These selections are repeated.  
Bits 0 and 1 together select the following functions:  
00  
01  
Selects RAMCard RAM read and RAM write-protect.  
Selects on-board ROM read. Two or more successive reads to the  
address write-enables RAMCard RAM.  
2 3  
10 Selects on-board ROM read and write-protects RAM.  
11 Selects RAMCard RAM read. Two or more successive reads  
to the address write-enables RAM.  
When ROM is selected, the Apple II on-board ROM is selected for the  
address space $D000-$FFFF. Refer back to the memory maps in Sec-  
tion 3.1 for an illustration of these relationships.  
Notice that it is possible to write to the RAMCard RAM and read from  
on-board ROMs at the same time (01 above).  
Bit 2 (the third column from the right) is ignored.  
Bit 3 (the left column) selects which 4K bank will be accessible. If bit 3  
is zero (x is between $t)-$3), then BANK 2 will be mapped into D000-  
$DFFF. If bit 3 is one (x is between $8-$B), then BANK 1 will be  
mapped into $D000-$DFFF. When one bank is selected, the other bank  
is not available.  
Power-on/RESET selects on-board ROM read (disables RAMCard  
RAM read), write-enables RAMCard RAM, and selects mapping of  
BANK 2 in the address space $D000-$DFFF. This is identical to two  
consecutive accesses of $C081  
-
The various selections are summarized in the chart below. Both the  
hexadecimal and decimal control addresses are shown in the first  
column.  
Control  
Address  
$C080  
Last Digit  
(binary)  
Functions/Bank  
Selected  
—16256  
0000  
Selects RAMCard RAM read, BANK 2, and  
RAM write-protect  
$C081  
—16255  
0001  
Selects Apple on-board ROM read, BANK 2,  
and write-enables RAMCard RAM if address  
accessed twice consecutively  
$C082  
—16254  
0010  
Selects Apple on-board ROM read, BANK 2,  
and RAMCard RAM write-protect  
2 4  
$C083  
16253  
0011  
Selects RAMCard RAM read, BANK 2, and  
write-enables RAMCard RAM if address ac  
cessed twice consecutively  
$C088  
—16248  
1000  
1001  
Selects RAMCard RAM read, BANK 1, and  
RAMCard RAM write-protect  
$C089  
—16247  
Selects Apple on-board ROM read, BANK 1,  
and write-enables RAMCard RAM if address  
accessed twice consecutively  
$CO8A  
-16246  
1010  
1011  
Selects Apple on-board ROM read, BANK 1,  
and RAMCard RAM write-protect  
$CO8B  
—16245  
Selects RAMCard RAM read, BANK 1, and  
write-enables RAMCard RAM if address ac-  
cessed twice consecutively  
NOTE: If RAMCard RAM was already in a write-enabled state, only a  
angle access of a write-enable control address ($C081, $C083, $C089,  
$C08B) is necessary to remain in a write-enable state until a write-  
protect control address is accessed. (This state applies immediately  
following power on.)  
Additional Technical Details  
The topics in these sections include status bits, the LED Indicators on  
RAMCard, and RAMCard hardware details.  
Status Bits  
Whenever a read is performed to any of the control addresses which  
alter RAMCard functions, the lower four bits of data returned show  
the status JUST PRIOR to the read.  
The four status hits (not to be confused with the bits of the control  
address) indicate:  
BANK SELECT When BANK I is selected, status bit 0 will be  
high. When BANK 2 is selected, status hit 0 will be low. This  
state applies immediately following power on.  
2 5  
 
READ ENABLE — When RAMCard RAM is read-enabled, sta-  
tus bit 1 will be high. When Apple on-board ROM is enabled,  
status bit I will be low. This state applies immediately following  
power on. When RAMCard RAM is read-enabled, an INH signal  
generated by the ICs in sockets U12 and U13 disable the ROMs  
on the Apple motherboard.  
WRITE ENABLE — When RAMCard RAM is write-enabled,  
status bit 2 will be high. The state applies immediately following  
power on. When RAMCard RAM is write-protected, status bit 2  
will be low. NOTE: Write-enable remains on until a write-pro-  
tect control address is accessed. Therefore, accesses to a write-  
enable control address subsequent to a write-enable will write to  
RAMCard RAM unless a write-protect access intervenes. This  
state applies immediately following power on.  
NEXT — To protect RAMCard RAM from accidental write-  
enable, two consecutive accesses to a write-enable control ad-  
dress are required. When the first access has been done, the  
NEXT flag is set, and status bit 3 is high. When the second access  
has been done and RAMCard RAM is write-enabled, the NEXT  
flag is turned off, and status bit 3 is low.  
LED Indicators  
Three LED indicators are attached to RAMCard along the top edge.  
Next to each LED is a label which describes the functions that the LEDs  
signal. The three labels are BANK 1, RAM READ ENA, and  
RAM WRITE ENA. The LEDs indicate whether the bank or function  
is on (selected) or off (deselected), but not whether an access is occur-  
ring or not. The LEDs indicate the following:  
LED  
ON  
OFF  
BANK I  
4K BANK 1  
selected  
4K BANK 2  
selected  
RAM READ ENA  
RAMCard RAM  
read selected  
Apple II ROM  
selected  
RAM WRITE ENA RAMCard RAM  
write-enabled  
RAMCard RAM  
write-protected  
The LEDs may be on or off in any combination because the banks and  
functions may be selected in any combination. At power-on/RESET,  
RAM WRITE ENA LED is on; the other two LEDs are off.  
26  
 
RAMCard Hardware Details  
This section describes how RAMCard handles its functions and indi-  
cates its States.  
The connector cable provides the RAMCard memory chips access to  
the multiplexed addresses and to a timing signal which is not available  
through the 50 pin I/O edge-connector.  
Addresses for RAMCard memory chips are provided by the Apple  
motherboard address mux. Data in and out for the single displaced  
chip (which is U9 on RAMCard) are routed through the connector cable.  
Data in and out for the other eight chips on RAMCard (in sockets U1-  
U8) are routed through the I/O edge-connector. The data out from the  
chips in sockets U1-U8 are buffered on RAMCard (by the ICs in sock-  
ets U19 and U20) to ensure sufficient drive capability. Control address-  
es and status information are routed through the I/O edge-connector.  
The decoding of the addresses and the storage of the state for each  
function are performed by the ICs in sockets U14-U18. The IC in socket  
U13 drives the LED indicators. Part of the IC in socket U19 buffers and  
selects the status bits during function selection. Once the state of each  
function is selected, the memory accesses on RAMCard are controlled  
by the ICs in sockets U ll, U12, U l5, and U18.  
2 7  
 
28  
 

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