kfl (03/29/83)
Subject: Notes on constructing the Heathkit H100 My local Heathkit dealer (Asbury Park, NJ) ogt his first shipment of H100's on March 10. A friend of mine and I broke down and bought one each. For those of you that are interested, the following are some general comments about the machine and building it. The hardware configuration I bought was the "low profile" kit, plus a second floppy drive and a 12" green monitor. Prices were: low profile kit $2199 second floppy $300 monitor $140 On top of that, we got a 10% discount on the hardware for buying two H100's, so the total system cost was $2375. For software I bought the 16 and 8 bit starter package ($500) that includes MS-DOS, CP/M-85, ZBASIC (which appears to be the same as IPM PC Advanced BASICA), and Multi-Plan (a spread sheet program like Visicalc). MS-DOS is the same as IBM PC-DOS and runs on the 16-bit 8088 CPU. CP/M-85 is for the 8085 8-bit CPU. I have seen the floppy drive (the H100 comes with Tandon 5.25 inch,double-sided, 48 tpi , 320K drives) advertised for about $250 and the monitor (Zenith) for about $100, so you might be able to do a little better on the price than I did. I would recommend getting the kit from a local dealer, so just in case something goes wrong, you can take it back for help. Heath dealers have a good reputation for technical assistance. The low profile kit comes in 3 boxes: one for the cabinet and guts, one for the floppy disk drive, and one for the floppy controller card. A technical manual set is also supposed to be included, but that won't be released until mid-April. Make sure you get all the boxes. My dealer initially didn't have the floppy drives or controllers, so he had to put in an express order to Heath for them. They came about a week later. Construction of the H100 was fairly straight forward. Being as careful as I could, I got the H100 build in 3 nights, about 11 hours total: 1 hour to verify the parts list (everything was there), about 6 hours to build the floppy controller card, 3 hours to assemble everything else, and less than one hour for calibration and testing. I was a little worried because there was so little testing done, and calibration was almost trivial, but after a week of running the thing, and using both CPUs, I am fairly sure that everything works. I guess with a project like this, if anything goes wrong, nothing will work. Documentation for the construction was very good. The instructions were easy to follow, very detailed, and well illustrated. They are also designed so that you can stop almost anywhere, and pick it up later with no problems. The floppy controller card was the most time consuming part of the construction. Except for a couple of wires on the power supply and one phono jack, all the soldering was on the floppy controller card. The card is pre-etched, but empty, so you get to solder in everything. All the chips go in sockets, fortunately. Watch your polarity (especially on the capacitors, because sometimes it's not too clear). All the H100 calibration involves the floppy controller card (adjusting 3 pots). You know you built the thing right when you read and write your first disks. (Also, try reading them in on someone elses machine, just to be sure). The rest of the H100 comes on pre-soldered boards (a mother board and a video board). If you bought the extra memory set or video RAM set, you get to install some chips on these boards, otherwise, you just bolt them in and plug in the connectors. You also get to assemble the chasis, which is pretty easy since the fit and finish are excelent. Everyting fits perfectly. The power supply is preassembled, except for a couple of ferrite beads that you get to install. Most of the tools required for the H100 are common: a small soldering iron, wire cutters, long nose pliers, a couple of phillips and a couple of standard screwdrivers (one very small). The only unusual equipment needed is a high impedence (20 megaohm/volt in the 1 to 5 VDC range) DC voltmeter. The voltmeter is used to calibrate the floppy controller card. No one I know owns a meter this good, but if you work for a major electronics or communications firm, or are associated with any reasonable university, you should have no problem borrowing one. Or maybe you can talk your Heathkit dealer into loaning you one (this calibration takes about 20 to 30 minutes). A few words about the hardware. There are 5 slots in the S100 bus. The floppy controller card goes in one slot, so you have 4 left for all those fun boards you see advertised in Byte. The back of the chasis has 11 expansion ports in several sizes, so you can buy whatever you want. Three I/O ports are build in: 2 serial (RS232) and 1 parallel (8 bit, for a Centronics type printer). These ports are on the mother board, so they do not take up a slot on the S100 bus. The floppy controller card can be configured for up to 4 disk drives (two 5.25 inch and two 8 inch). The keyboard has 95 keys, including a separate numeric keyboard. It has a much better layout than the IBM PC, but it is not detachable like the PC. The keyboard also has 12 function keys, 2 editing keys. It has a 8041A CPU, 17 character FIFO buffer, optional key click, and 2 auto repeat speeds. Video output is 25x80 characters or 640x225 pixels. The character set is dynamically redifinable and font sets are available for a number of foreign languages. Options include 8 color RGP (or 8 level grey scale for monochrome monitors), 2 page display, and a light pen. In addition to the construction documentation, the H100 includes techinical info on the system (not yet available), tutorial information (several hundred pages) on the H100, computing in general, ZDOS, CP/M, and ZBASIC. Also includes is a demonstration floppy with a graphics demo and a business demo. Thats all for now. If there are any questions or comments, please let me know. I think the H100 is a bargain for what you get. It costs much less than the IBM PC, but is more powerful and more expandable (in my opinion). Kenton Lee BTL West Long Branch, New Jersey harpo!mhuxt!kfl eagle!mhuxt!kfl