Wouter's Apple Macintosh page

Macintosh the first

I bought my first Apple Mac from Cash Converters for R200.

Before this, all of my Apple experience was with the Apple ][+, and I didn't know squat about Macs. This one turned out to be a bit of a mystery. The case is marked Mac Classic II (M4150, CK2040HVD15), but the motherboard is the standard 68000 Classic (M0420). It had 4MB RAM and a 40MB Quantum hard drive. So...

How to install a bigger hard drive in your Mac Classic

There are basically two issues here, namely

  1. How to get software from the Internet to the Mac, and
  2. How to format the hard drive.

The first is not too much of a problem, since the Mac Classic has a 1.44M floppy drive. Older macs used the 400 and 800k drives with Woz' special RLL encoding, which can't be accessed by anything except a Mac. You'd probably have to "bounce" through a Mac that can read 1.44M floppies and write 800k ones.

OK, first things first. You need a system disk. System 6.0.8 is probably the best for a Classic Mac.

I downloaded two files from Apple, namely SSW_6.0.8-1.4MB_Disk1of2.sea.bin and SSW_6.0.8-1.4MB_Disk2of2.sea.bin.

Drag-and-dropping these files into Aladdin Expander 5.1 (ALEX511.EXE) gives two .sea files, and repeating the process gives two files with no extension and length 1 474 644.

I opened these files using Cygnus Hex Editor and chopped off the first $54 (decimal 84) bytes, save as .dsk (1 474 560 bytes long). These .dsk files can be written to stiffy using HFVExplorer 1.3.1 (hfvexplorer131.zip).

You can also use VMac to manipulate files inside the .dsk images before writing the .dsk to disk.

Formatting a new hard drive

You need third party software to format any non-Apple hard drive. As far as I know, the following will all work :

I used Lido 7 and it works well. If you open lido756.hqx with HFVExplorer (copy it from your PC drive to one of the virtual volumes), you will end up with a lido7.56.sea file. Double click on this file in VMac (or I guess on a real Mac :-) to extract the archive.


The Mac Classic has 1MB on the motherboard, and a space for an expansion card with another 1MB soldered to it, as well as space for two SIMMs.

My Classic came with 4MB of RAM installed. This is also the maximum, the (stupid, IMO, but hey, hindsight is the only exact science) reason being that the ROM is mapped at $400000.

Macintoshes the second to fifth

2004-02-02: I bought four Macs for R300.

The Mac Plus was sold with 256K of memory, but mine have been upgraded to 1MB (4 SIMMs total).
Serial #Model NumberPCB IDPCB Serial #Pictures
930512512MP (?)M0001A Plus 820-0174-DSG93307S212A 
E915Q0BM5880 Singapore, number 27755 of week 15 1989M5880 Plus    
F834CX5M0001A Fremont, number 14931 of week 34 1988M0001A Plus    
SG0400CD11 Singapore, number 422 of week 40, 1990M0420 Classic 820-0390-03SG046RC803F3 
CK2040HVD15 Cork, number 607 of 4th week 1992M4150 Classic II 820-0390-BCK2023KT044C 

More Macintoshes

2011-11-10: I was looking around for Macintoshes and found two more. No idea where I got them from. They're just... here. Strange.

Anyway, the first is a Macintosh M0001P, with jumpers for 128k or 512k on the motherboard, which means it's the somewhat later motherboard in the early style case. Opening it up shows that someone's been here before me, the floppy cable is missing, The RAM has been replaced with 256 kbit devices to give 512 kbyte instead of 128 kbyte, the serial drivers and ROM chips are in sockets, and the ROMS are 27C512 EPROMS labelled "Rom Lo 0AE0" and "ROM HI C818". This Mac has a Hitachi 68000 processor.

The second is a Mac SE "FDHD", except it's fitted with two floppies, no hard drive, nothing in the expansion slot, and 1 MByte of RAM. It also has mismatched ROMS -- The high ROM and the low ROM are from different manufacturers.

Serial #Model NumberPCB IDPCB Serial #Pictures
 M0001P 820-0141-AL40031532
F933FY5B03 Fremont, number 18433 of week 33 1989M5011A 820-0250-ABS9047223

Hardware information

Mac Plus

While the original Macintosh had 128k RAM, the motherboard design (see schematic) allowed for 512k.

Upgrading the 512k "Fat Mac" needed a redesigned motherboard. This was the "Plus", with 1MB on the motherboard, which could be expanded to 4MB (Scans of PCBs).

The original 512k design and the Plus makes extensive use of PAL technology. See http://www.mactech.com/articles/mactech/Vol.01/01.11/PAL/.

Kryten Droid (http://homepage.ntlworld.com/kryten_droid/) has had some info on what's inside the PALs. Fortunately I have a backup.

512K MAC:
ASG  16R8 Disk speed control, sound generator.
BMU0 16R4 Ram control (read, write, DTACK)
BMU1 16L8 Address decoding
LAG  16R8 Video generator
TSG  16R6 Divide by 2, divide by 4.25.
TSM  16R4 Generates RAS and CAS for DRAM
Mac Plus:
ASG  16R8 341-0517-A
BMU1 16L8 341-0514-A
BMU2 20R4 341-0520-A
CAS  20L8 341-0519-A
LAG  16R8 341-0515-A
TSG  16R6 341-0516-A
TSM  16R4 341-0522-A
Datasheets at Texas Instruments: 16L8, 16R4, 16R6, 16R8, 20L8, 20R4, 20R6, 20R8.

Reverse Engineering the PALs.

The Plus uses 9 bit SIMMs, while the Classic uses 8 bit SIMMs.

ROMs in my Plus are 342-0341-C (hi) and 342-0342-B (lo). Read these using the settings for 27C512.


The Classic is a Plus using surface-mount technology on a smaller (half the size) motherboard (Scans of PCBs). The six PALs are replaced by a gate array from VLSI (UI4, BBU) and one PAL (UL1, CAS PAL). A fan was added, presumably because of the extra heat from the internal hard drive.

The ROM is a 40 pin 16 bit device from Sharp. The Apple part number for the ROM in my Classic is 341-0813. The pinout matches the Amiga ROM, which is a Macronix MX23C4100. If you want to read your ROM using a programmer, use the settings for the 27C400.

The two motherboards I have are 820-0390-03 (1990, Assembled in Thailand) and 820-0390-B (1990, 1991, Assembled in Ireland). The only differences I can spot are in the silkscreen. The same components are used in the same places and as far as I can see the board was not rerouted -- all the tracks are identical.



[Image] Hit Count
hits since 2004-02-02

Back to Wouter's CCC Page (This page last modified 2017-02-09)