Jump to content

Apple II Memory Expansion Card

From RetroTechCollection
Apple II Memory Expansion Card
A card filled to 1 MB, board 670-0024-A, © 1985
Manufacturer Apple Computer
Type RAM disk card
Interface Apple II peripheral slot
Compatible Apple IIe (preferably enhanced), Apple II Plus, Apple II; RAM disk only in the Apple IIGS
Model A2B2086
Power +5 V; 100 mA operating at 256K, 200 mA at 1 MB
Part number 670-0024 (board)

The Apple II Memory Expansion Card is a slot card that adds 256K to 1 MB of RAM to an Apple IIe, Apple II Plus or Apple II.[1] Apple's order number was A2B2086.[1] It works as a RAM disk with its own firmware, not as extra main memory. Apple's IIe service manual also calls it the Apple IIe Memory Expansion Card.[2] Apple sold two sibling cards at the same time: the Apple IIGS Memory Expansion Card and the Apple IIc Memory Expansion Card.[1]

Apple II Memory Expansion Card power consumption
Size Operating Standby
256K 100 mA 50 mA
1 MB 200 mA 150 mA

The figures are Apple's, at 4.75 to 5.25 V.[1][3] Apple saw no need for a bigger power supply in a IIe with extra memory fitted.[4] See Apple II Memory Expansion Cards Documentation for the manuals.

How it works

[edit | edit source]

The card does not add to the memory the 6502 can address. Programs reach it in two ways: as a RAM disk, or through calls that follow the protocol converter conventions of the IIc's external disk port.[3][5] The first time it is accessed after power-on, the firmware formats it for whichever operating system started the machine: ProDOS, DOS 3.3 or Pascal.[5][6] Under ProDOS it becomes the volume /RAMn, where n is its slot.[5] Everything on it is lost when the power goes off, and the card has no battery backup.[2]

The card cannot stand in for the IIe's Extended 80-Column Text Card or the II Plus's Language Card. Programs that need 128K on a IIe, or 64K on a II or II Plus, still need those cards.[1] Starting programs directly from the card needs an enhanced IIe.[1] On an unenhanced IIe a ProDOS program in 80-column mode can leave the card unformatted for the next program; format it with the ProDOS User's Disk, or switch off between programs.[5]

Apple's technical note records a firmware bug: the code at $Cn5A compares the wrong register (CMP #4 where CPY #4 was meant). Apple left it unfixed in the card's ROM. A DOS-formatted card also stays DOS-formatted until the power is switched off.[6]

Hardware

[edit | edit source]

The board in the photograph is 670-0024-A, © 1985. It has 32 RAM positions in two rows, A and C, numbered 1 to 16, a custom gate array numbered 344-0601 and a 2732 EPROM labelled 341-0344A.[7] The card in the photograph is full, with Fujitsu MB81256-15 chips (256K × 1, 150 ns). Apple's service manual told technicians to fit only Apple RAM, which has an A printed near pin 1.[2]

Fitting the card

[edit | edit source]
  1. Switch the computer off, but leave it plugged in.[5]
  2. Remove the cover and touch the power supply case to discharge static. Apple warns that the card's chips are very sensitive to static.[2]
  3. Insert the card in any free slot except slot 3 or the IIe's auxiliary connector. On a II Plus, slot 0 holds the Language Card.[5][2]
  4. Use slot 4, 5 or 6 if any of the programs are Pascal-based.[5]
  5. To start programs from the card when the computer starts up, put it in a higher-numbered slot than the disk controller, because the startup scan begins at slot 7. Otherwise type PR#n from BASIC.[5]

Adding memory

[edit | edit source]

Each Apple 256K Memory Expansion Kit (A2M2058) holds eight chips: one kit for 512K, two for 768K, three for 1 MB.[1] Each kit fills the next group of eight sockets shown in Apple's chart. Fit each chip with the end marked A pointing away from the gold fingers.[5][2] Apple recommended dealer installation.[1]

Testing

[edit | edit source]

The card has a test in its firmware. It erases whatever is on the card.[5]

  1. Start the computer with no disk in drive 1 and press Control-Reset.
  2. Type CALL -151 and press Return.
  3. Type Cn0AG, where n is the slot, and press Return.[5][8]

The screen shows the card size found and a pass count, and the test repeats until it finds an error or Escape is pressed. One pass takes 45 seconds per 256K, so 180 seconds for 1 MB.[8] Apple's dealer diagnostic disk has its own test, in the RAM Tests folder of the IIe diagnostics.[2]

Reading the error codes

[edit | edit source]

Errors appear as ADDRESS ERROR or DATA ERROR followed by a code of the form XXYYYY-ZZ.[8] An address error usually means the card itself has failed. A data error usually means a RAM chip: ZZ gives the group of four chips and XX the chip within it. Ignore YYYY.

Apple II Memory Expansion Card data error codes
ZZ (row C) ZZ (row A) XX 0C-0F XX 08-0B XX 04-07 XX 00-03
10 01 C1 / A1 C2 / A2 C3 / A3 C4 / A4
20 02 C5 / A5 C6 / A6 C7 / A7 C8 / A8
40 04 C9 / A9 C10 / A10 C11 / A11 C12 / A12
80 08 C13 / A13 C14 / A14 C15 / A15 C16 / A16

In Apple's worked example, printed as DATA ERROR 08000-40, section 40 points to C9-C12 and locator 08 to C10.[8] Row A is the top row of the card and row C the bottom.[2] Apple's December 1985 service mailing printed the chart wrongly; the version in the Tech Info Library is the corrected one.[8]

Other section codes (0B, 0E, FC and so on) usually mean a card failure. A code can also point at a socket with no chip in it: for a 256K card reporting 0C0000-40, Apple's advice is to change the RAM fitted in that section, then in the neighbouring sections if the error stays. If the test reports a smaller size than the card holds, for example 768K on a 1 MB card, swap the eight chips at A1, C1, A5, C5, A9, C9, A13 and C13 for known-good ones and retest, then put the originals back one at a time to find the bad one.[8]

Apple's exchange cards came without RAM. Technicians moved the customer's chips onto the replacement and kept faulty chips out of the returned card.[2]

In the Apple IIGS

[edit | edit source]

In the Apple IIGS the card works in a peripheral slot, but only as a RAM disk named after the slot, such as /RAM4. It does not add to the IIGS's memory; the Apple IIGS Memory Expansion Card does that.[9][10]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Apple Computer, Apple II Memory Expansion Cards data sheet, July 1987, A2F2222, pp. 53-56. Hosted as File:Apple II Memory Expansion Cards data sheet (A2F2222, July 1987).pdf. Source for: the three Apple cards and the machines each is for (p. 53); the Apple II card shipping with 256K and upgradeable to 512K, 768K or 1 MB, dealer configuration recommended, starting applications from the card needing an enhanced IIe, not usable in the IIe auxiliary slot or in slot 3 when the auxiliary slot is occupied, no substitute for the Extended 80-Column Text Card or the Language Card (p. 54); system requirements and power consumption (p. 55); order numbers A2B2086 (card) and A2M2058 (Apple 256K Memory Expansion Kit) (p. 56).
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Apple Computer, Apple IIe Technical Procedures, Section 6 "Apple II Memory Expansion Card", pp. 6.1-6.4 (PDF pp. 52-55), dated Dec 85 to Feb 87: the memory configuration chart; ESD warning; exchange modules shipped without RAM; only Apple RAM, marked A near pin 1; ProDOS RAM disk; slots 4-6 for Pascal; any slot but 3 on the IIe, not slot 0 on the II Plus; no battery backup; the diagnostic disk test and the A1-A16 and C1-C16 chip coordinates. Section 2, p. 2.12, lists the Apple IIe Memory Expansion Card Test. Hosted as File:Apple IIe Technical Procedures.pdf (see Apple IIe Technical Procedures).
  3. ↑ 3.0 3.1 Apple Computer, Tech Info Library article 7883, Apple II Memory Expansion Cards: Decsription (11/96) [sic], created 31 May 1991, absurdengineering.org library. The three cards; compatibility with ProDOS, DOS 3.3 and Pascal 1.3, DOS 3.3 programs not bootable from the card; voltage and power figures; the card accessed only as an Apple protocol converter device or as a RAM disk.
  4. ↑ Apple Computer, Tech Info Library article 7612, Apple IIe: Memory and the Power Supply, 18 April 1991, absurdengineering.org library.
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 Apple Computer, Apple II Memory Expansion Card User's Manual, © 1985, for the Apple II, II Plus and IIe. Hosted as File:Apple II Memory Expansion Card User's Manual (1985).pdf. About the card (p. 2); installing (p. 3); how it works and the unenhanced IIe exception (p. 4); ProDOS, Pascal 1.3 and DOS 3.3 (p. 5); starting up from the card (pp. 6-14); Appendix A, diagnostic test (p. 16); Appendix B, assembly-language interface (p. 17); Appendix C, Apple 256K Memory Expansion Kit installation (p. 18); Appendix D, testing the card (p. 19).
  6. ↑ 6.0 6.1 Apple Computer, Developer Technical Support, Apple II Technical Notes: Memory Expansion Card #1, Questions and Answers, written by Cameron Birse (April 1986), revised by Mike Askins and Matt Deatherage (November 1988), archive.org item APPLE_II_Technical_Notes-Memory_Expansion_Card_2523001_QA, https://archive.org/details/APPLE_II_Technical_Notes-Memory_Expansion_Card_2523001_QA (retrieved 2026-10-04). Screen holes used by the firmware; RESET turning the registers off until a $Cn00 access; self-formatting on any firmware access; the $A0 screen-hole check; the CMP/CPY bug at $Cn5A; DOS formatting persisting until power-down.
  7. ↑ Applelogic.org, "Peripheral Cards", Apple II Memory Expansion Card entry, http://www.applelogic.org/PeripheralCards.html (retrieved 2026-10-04): Apple model number 670-0024; parts A18 344-0601 and C18 341-0344A (2732 ID ROM); photograph AIIMEMEXPHIRES.jpg; schematic and manual links.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Apple Computer, Tech Info Library article 1569, Apple II Memory Expansion Card: Diagnostics (11/96), created 16 December 1985, absurdengineering.org library. Running the built-in test from the monitor; 45 seconds per 256K; the card size and pass count; address, data, non-existent RAM and card size errors; the error code chart, with corrections to the December 1985 mailing; the worked example; the eight chips to swap for a card size error.
  9. ↑ Apple Computer, Tech Info Library article 611, Apple II Memory Expansion Card: Using it on the Apple IIGS, last reviewed 14 September 1987, absurdengineering.org library. Not usable as IIGS RAM; appears as a ProDOS volume named after its slot; the IIGS DeskTop program loads itself into it.
  10. ↑ Apple Computer, Tech Info Library article 8232, Apple IIGS: Contiguous RAM Depends on Memory Board, 14 May 1991, absurdengineering.org library. GS/OS and ProDOS make the card a RAM disk at startup.


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Apple_II_Memory_Expansion_Card&oldid=23955"