Hazelwood Computer Systems Helix SS64 system (board)  - Page 1
Forum section: electronics / projects

author: W0MJ
author_rank: Contributor
timestamp: May 27, 2020, 09:56:50 pm
content: Anyone have *any* information on the Hazelwood Computer Systems Helix SS-64 buss (enhanced SS-50) motherboard / system? I have the motherboard but it (unfortunately) got to me without a single chip installed! I have *most* of it figured-out (buffering, I/O select), but the baud-rate division chips (U16 - U19) are a mystery... it uses an 8-MHz crystal and a 7404 oscillator, and a single 'chip' to deliver a 38.4 line to the SS-30 (I/O-side) buss - divide by 13? Then three more ICs to divide down for 19.2, 9600, 4800, 2400, 1200, (600, 300) and 110 bps clock.The motherboard is rather large and has a built-on power supply, 15 I/O SS30 buss positions, gold pins, and a spot for two full-size 5.25" diskette drives, and power cables for them. Also, two serial ports (6850) and two parallel ports (6821) on the motherboard.Hazelwood Computer Systems was a local computer shop / manufacturer here in the St. Louis, MO area (Hazelwood, MO) until the late 1980's (maybe a little longer), but Mike Smith dropped-off the planet. He made a move out to Rhineland, MO at some point, and the phone-number I have is not longer any good. I cannot find a website. The last address I have (on a sales flyer) for the UniQuad and K-Kits is:Hazelwood Computer SystemsHighway 94 at BlufftonRhineland, MO 65069(314) 236-xxxx*ANY* help appreciated!Thanks,-Matt W0MJ

author: W0MJ
author_rank: Contributor
timestamp: May 28, 2020, 11:52:04 am
content: picture of the motherboard...

author: phil from seattle
author_rank: Super Contributor
timestamp: May 28, 2020, 05:24:56 pm
content: Wish I could help you on the schematic and such. I'd start by looking at what kind of processor it supported and look for the support chips. There may be application notes from the manufacturer that the guy designed from. I doubt he went far off the "ranch" with his design so it's probably pretty standard for the era.Edit: SS-50 was for a 6809. I would bet the SS-64 was for 68000 designs (early 1980s) so go spelunking in Motorola app notes. I bet a lot is laid out there.

author: srb1954
author_rank: Super Contributor
timestamp: May 29, 2020, 05:08:33 am
content: Can you do an enlarged photo of the area of the board where the chips are missing?It should be pretty easy to figure out the dividers for the 19200 down to 300 baud. These will simply be divided down from the 38400 baud clock using a 4-binary counter such as a 74xx93 or the dual version 74xx393 (where xx is the logic family of your choice LS, HC etc). Another option is a 7-bit binary counter such as a 4024. Trace out the wiring to the sockets and see if it matches the pin-outs of these devices.The 110 baud output is a little more tricky. This requires a non-binary divider and is possibly derived by dividing the 1200 baud clock by 11. This will require another 4-bit binary counter (74xx93) together with some gates or possibly just a presettable 4-bit binary counter such as a 4029. Trace back from the 110 baud output and try and match the pin-out of the chip with some of these devices.Stephen

author: W0MJ
author_rank: Contributor
timestamp: May 29, 2020, 04:44:17 pm
content: The divide by 13 is the tough one; the rest will fall into place!No schematic, it is part of what i would like to have; and no, I have not traced-out the sockets (yet).If I can get 38.4, 19.2 and 9600, do not really need much more.8-MHz crystal with 74LS04 as the oscillator.Thanks!

author: srb1954
author_rank: Super Contributor
timestamp: May 30, 2020, 02:44:42 am
content: The fact that the remaining empty sockets are all 16-pin eliminates some of the possibilities for the chips. The division of the 38400 baud clock down to 19200, 9600, 4800 etc is most likely done by a 74LS393 - the 74LS93 and 4024 are eliminated from consideration since they are 14-pin devices.The apparent absence of pull-up resistors around this area also eliminates the possibility of a mixed TTL and CMOS design. With the age of this board it would be fairly safe to assume that only 74LS series devices are used.Conventionally division by non-binary division factors of 11 and 13 are obtained by using gating to decode the outputs of a 4-bit binary counter and using this to force the counter into a shorter count cycle. Since almost all 74LS gate packages are 14-pin packages and there are no 14-pin sockets it can be assumed that the decoded binary counter method is not being used. That leaves the use of a presettable counter such as 74LS161, 163, 191 and 193 as the most likely candidate for the non-binary dividers.Best approach would be to trace out crystal clock signal to one of the empty IC sockets and comparing that with the clock input pin of the above mentioned chips.StephenThe

author: W0MJ
author_rank: Contributor
timestamp: June 03, 2020, 09:51:54 pm
content: Looks like a 74LS187 with a 74LS10 (on Q3, Q2 and Q0 (1101)) - divide by 13. Then, another 74LS197 to divide by two, four times.Got it!Still looking for any information from Hazelwood on any of the Helix products.Thanks!

author: W0MJ
author_rank: Contributor
timestamp: June 04, 2020, 12:50:36 pm
content: 74LS197, not 74LS187!mistyped that...

author: W0MJ
author_rank: Contributor
timestamp: January 12, 2025, 01:42:43 am
content: Still looking for ANY information or hardware from the Hazelwood Helix computer system…SS64 chassis/buss, a modification of the SS50 format (SWTPC). Additional address, control and data lines to support the Motorola 68000, above and beyond the 6809.Help!?Thanks.-Matt W0MJ

author: CaptDon
author_rank: Super Contributor
timestamp: January 12, 2025, 02:21:13 am
content: Their was a very nice gentleman named Christopher Titus living in Blacksburg Virginia. His phone number was listed in the directory. He wrote several books on 8080/8085 assembly language, one being named TYCON Editor Assembler which I have running on an 8085A (SDK-85) Intel board. If I remember correctly he not only has/had a computer museum be he bought my fully working Intellec 8/MOD80 at the Gaithersburg Maryland ham radio hamfest about 25 years back!! He looked like a little kid on Christmas morning!!! He may have also gotten my Friden 8-level tape reader and tape punch. If you can find him he may be able to help. There is also an online computer museum website and they may offer some leads for you. I had a friend who was a tech and design engineer for Zilog and they were big in the SS-50 industrial buss manufacturing many different cards for SS-50 and possibly SS-64. There was also the really popular S-100 buss. Intel offered their own mini-computer backplane although I forget the trade name.

author: W0MJ
author_rank: Contributor
timestamp: October 17, 2025 01:28:59 am
content: Hazelwood Helix is up and running with a SWTPC 09 CPU, Hazelwood DM-64 RAM card and SWTPC DC-4 diskette controller card. Decided it was easier to put the baud rate lines (14411 and crystal, 74L04 buffer) on a proto card on the SS-30 side than figure out the clock divider ICs.BIG board with power supply built-in. Runs 5.25” and 3.5” diskette drives (2 of each).Still no case or other info, except ads from 68MicroJournal.Any info appreciated!Thanks,-Matt. W0MJw0mj@arrl.net