Notes on Mac8 Martin Eberhard Machine The particular machine I bought is a Mac8 EMIC Alpha/S-100. The guy who sold it to me said 2 interesting things: 1) this machine was made to run on Japanese line voltage, 100V rather than 117V as we have in the USA. Problems will occur if I try to run it on 117V. 2) The manual is all in Japanese and is therefore useless. Taking his precaution, I bought a Japanese 117v-100v step-down transformer for this machine. When I got the machine, it was nonfunctional. Restoration required the following: 1. 7 switches on the front panel had to be replaced becasue they were broken, or because they had previously been replaced with switches that did not match at all. The replacement I installed are close to the original switches, but not perfect. 2. The NEC 8080A CPU chip had corroded badly into its socket, to the point where several pins were no longer continious. The socket and the CPU chip had to be replaced. 3. The Vcc voltages on the front panel were way high. One regulator was producing 6.3V, the other 7.5V. Both had significant 60Hz noise. The problem turned out to be that the regulators (and their heat sinks) were installed on the wrong side of the board, resulting in the input and output pins being swapped. Mac8 intended the regulators to be installed on the solder-side of the board. But since the guy who assembed this machine couldn't read Japanese, he missed this instruction. Moving the regulaors and heat sinks the the solder side fixed the front panel Vcc. The original 7805 regulator ICs were still ok, as were all the front panel chips. I speculate that this mistake is the root of his comment about Japanese line voltages: as he had built it, the front panel Vcc would rise proportionally with line voltage. 4. On the 4K RAM board, C3 had failed. This is the 33 uF/16V electrolytic capacitor on the input of the regulator. Its top was bulging, and it had spewed electrolyte onto the board, causing corrosion of nearby components. This capacitor was replaced with a 100 uF/30V electrolytic capactor. 5. Mounting screws were missing for the power supply board. These were replace with similar screws. 6. Everything was cleaned. Mac8 Computers Mac8 (sometimes called McEight) is a Japanese company that made several computers in the late '70s and early '80s: EMIC Series The EMIC series included three variants with the same chassis: 1) The Emic Alpha was an 8080A-based machine that used a Mac8-propietary bus. This bus was abbreviated in the Mac8 literature as 'ORG', which may stand for 'Original'. 2) The EMIC Beta was a 6800-based machine also based on the ORG bus. 3) The EMIC Alpha/S-100 was an 8080A-based machine based on the S-100 bus. Note that although the machines looked similar, the front panel boards in these three machines were each unique. PAL Series Mac8 also made a series of computers called the PAL series. This series was built from enclosed modules that could be directly plugged into each other to add peripheral functionality. Internally, these modules were S-100 based. Modules included: 1) PAL-CPU module included the EMIC ROM on CPU/S-100 board (with a ROM-based monitor0, the EMIC 4K RAM/S-100 board, the EMIC Serial IO/S-100 board, and an optional EPROM programmer atachment (?) on its front. 2) PAL-EXT module addes 6 S-100 slots 3) PAL-CRT included the EMIC Video-RAM (I)/S-100 board, as well as a small monochrome screen. This provided 1K of video memory for a 16X64 display, with 5X7 characters. 4) PAL-CMT was a cassette tape inerface, and included the EMIC CMT Controller, as well as a TEAC MT-2 cassette tape transport. This module came with a 2708 EPROM that was to be installed in the ROM on CPU board in the PAL-CPU module. Data was recorded at 800 bpi. The transport could move at either 15 ips (for 1200 baud read and write speed) or 45 ips (for seeking). 5) PAL-FD inclided the EMIC FD CONT/S-100 floppy controller board, as well as a Shugart SA400 5.25" floppy drive (35 tracks, 16 sectors per track, 128 bytes per sector). This module came with a ROM to be installed in the PAL-CPU module. 6) PAL-Console Panel was a front panel module for the PAL series. Macro/80 The Macro/80 was a rack-mounted S-100 system with integral SA-800 8" drives. It ran CP/M. Intelligent PAL Was a complete Z-80-based CP/M system with keyboard, monitor, 1 SA-400 floppy drive, and a modem. It had 3 S-100 slots. S-100 Boards Mac8 made the following S-100 boards (in addition to a line of ORG boards). EMIC CPU-8080A/S100 (2 MHz 8080A CPU) EMIC CPU-6800/S-100 (6800 CPU) EMIC ROM on CPU/S100 (2 MHz 8080A CPU with 4 2708 sockets and a vectored interrupt connector) EMIC 8K ROM/S-100 EMIC 2K RAM/S-100 EMIC 4K RAM/S-100 EMIC 8K RAM/S-100 EMIC 16K RAM/S-100 EMIC Video-RAM-(I)/S-100 (1K video RAM and a 5X7 character generator) EMIC Serial IO/S-100 EMIC Parallel IO/S-100 EMIC Programmable IO/S-100 EMIC Isolator IO/S-100 EMIC CMT CONT/S-100 (TEAC cassette tape controller) EMIC Universal Card/S-100 DIP (Proto board for DIP packages) EMIC Universal Card/S-100 DOT (Proto board with 0/1" plated hole array) EMIC Extender Card/S-100 (extender card) Company As of January, 2014, Mac8 is still in business in Japan as Mac-Eight Co, Ltd. They make PC boards, counting and timing equipment, and some components. Their website is www.mac8.co.jp. Their phone number is only slightly changed from the 1980-ish brochure. It was 045(543)1161. Today it is 045(583)1161. I suspect this change represents only an area code split. Their English-language distrubutor (in Japan) is Shindenkizai Co, Ltd (www,mac8japan.com) at 2-2-13 Sotokanda Chiyodaku Tokyo, Japan 101-0021. In the Media See Creative Computing, Nov-Dec 1978 (Vol. 4, no. 6), page 32. On the Web http://www.st.rim.or.jp/~nkomatsu/s100bus/EMICSIO.html shows a serial board