MacintoshPortable8MB RAM
About the MacintoshPortable8MB RAM PCB
MacintoshPortable8MB RAM is an open source PCB design by 2tf2294x4g-maker, published on GitHub under the CERN-OHL-S-2.0 license. It is a 4-layer board measuring 123 × 81 mm, with 38 components from 12 distinct parts.
Other key parts include the ATF1502ASL-25AU44, AS6C8008-55ZIN and SN74HC245DW. By type, the board carries 19 capacitors, 11 ICs, 4 resistors, 2 connectors, 1 jumper and 1 test point.
From the project
Mac Portable Variable 4 or 8MB RAM expansion card — all-5V, AS6C8008 SRAM, ATF1502ASL CPLD. Expands to 9MB total (system max).
Expands a Macintosh Portable to 9 MB total (1 MB onboard + 8 MB this card) — the maximum the Portable's address space supports.
All-5V design using 1M×8 SRAM chips. No level shifters, no LDO regulator, no 3.3V rail. Shares the same connector, CPLD, and bus transceiver approach as the 4MB card but doubles capacity using larger SRAM.
The AS6C8008 (8MB card) and AS7C4096A (4MB card) are both TSOP-II-44 but have different pinouts. Do not install 4MB card SRAM chips on this board — the CE#, WE#, and OE# pins are in different locations and the board will not work correctly.
Main components on the MacintoshPortable8MB RAM
MacintoshPortable8MB RAM bill of materials (BOM)
38 components, 12 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | ATF1502ASL-25AU44 ATF1502ASL Microchip | TQFP-44_10x10mm_P0.8mm | U1 |
| 8 | AS6C8008-55ZIN Alliance Memory | TSOP-II-44_10.16x18.41mm_P0.8mm | U2, U3, U4, U5, U6, U7, U8, U9 |
| 2 | SN74HC245DW 74HC245 TI/Nexperia | SOIC-20W_7.5x12.8mm_P1.27mm | U11, U12 |
| 1 | BCS-125-F-D-HE RAM Connector Samtec | Samtec_BCS-125-F-D-HE | J1 |
| 1 | JTAG_Header_2.54mm_1x06 Generic | PinHeader_1x06_P2.54mm_Vertical | J2 |
| 1 | JP1: open=8MB closed=4MB Generic | PinHeader_1x02_P2.54mm_Vertical | JP1 |
| 1 | GND | TestPoint_GND | TP1 |
| 12 | 100nF | C_0805_2012Metric | C1, C2, C3, C4, C5, C6, C7, C8 +4 |
| 4 | 10µF | C_0805_2012Metric | C13, C14, C15, C16 |
| 2 | 100NF 100nF Generic | C_0805_2012Metric | C17, C18 |
| 1 | 10UF 10µF Generic | C_0805_2012Metric | C19 |
| 4 | 10K Generic | R_0805_2012Metric | R2, R3, R4, R5 |
MacintoshPortable8MB RAM design files
The KiCad project lives in the 2tf2294x4g-maker/MacintoshPortable8MB_RAM repository on GitHub; these links point at the commit this page was built from.
MacintoshPortable8MB RAM: common questions
How big is the MacintoshPortable8MB RAM PCB?
The MacintoshPortable8MB RAM measures 123 × 81 mm, has 4 copper layers and is 1.625 mm thick.
How many components are on the MacintoshPortable8MB RAM?
38 components, from 12 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the MacintoshPortable8MB RAM design files?
From the 2tf2294x4g-maker/MacintoshPortable8MB_RAM repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the MacintoshPortable8MB RAM design in my own project?
Yes, under the terms of its CERN-OHL-S-2.0 license, which 2tf2294x4g-maker chose for the repository.