Most recent revision of this page June 21 2024(c) Herb Johnson. This Web page is preliminary, work in progress.
In April 2023 I purchased a damaged Cromemco JS-1 joystick. About a year later in May 2024 I came across a Web discussion on producing a replica JS-1, and images of original JS-1's. So I began to restore mine, and to produce a close replica from parts I could gather. I found useful information on the deskthority Web site and their Wiki, about the JS-1 and parts. Another JS-1 teardown and replica, was found on the s100computers.com Web siteSome photos on this Web page are from those sources.
I have lists of Cromemco documents and further Cromemco notes at this Web link.
Note: This is a preliminary Web page to show my work and progress. Caution: if you find details about parts and part-hunting tedious, this is not a Web page you'll enjoy. - Herb Johnson
Original as found
Case cleaned up, joystick pulled
Opened cabinet before cleaning
inside base of cabinet after cleaning
rough dimensions of cabinet
rough dimensions of key hole and keycap
interior, from s100computers.com site
exterior, from deskthority site
Cromemco edge connector housing, deskthority
deskthority JS-1 Joystick discussion
unassembled JS-1 parts, from vcfed.org discussion
My JS-1 joystick:
Opened cabinet
another interior view
JS-1 schematic
Joystick cutout, note corrosion damage
Joystick case, back w/speaker holes, screws
Speaker
joystick, top of assembly, under of silvered cap
top and bottom of keycaps
Keystem view of Cherry keyswitch
Kraft R/C control from ebay, black square joysticks
Futaba R/C control I acquired, with silver joysticks.
Original Cherry keycap on left, new old-stock on right
Original Cherry on left, new old-stock on right
Original Cherry keyswitch, from deskthority
terminal strips from eBay
Hammond case on left vs. Cromemco on right, cases
Joystick feet & screws, upper are original, lower from pulled old parts
PC parallel cable, colored wires like JS-1 cable
cable exterior, JS-1 vs PC cable
Here's a link to the long discussion thread (18+ pages) about creating a replica JS-1 Cromemco joystick. The beginning of the thread illustrates the situation, shows photos of various found parts. My discussion below, is partly based on the forum's findings, and my own findings. I've acquired more than enough parts, and determined sources for them, so ask me for parts I've described or for other parts.- Herb
The Cromemco chassis is two-part. A U-shaped cover that's about five inches square and few inches tall, sloping top. No holes needed in the blue base, a thicker U-shape. The cover needs four square holes about 1" square for keyswitches, and a 2-inch circle and two slots along side for joystick. These are rough numbers to size up the job. Also, 25 drill holes for the speaker. A recent chassis replacement from Hammond, has similar colors and dimensions, but oval air-slots not on the Cromemco chassis. The discussion goes thru many rounds of making measurements. What matters for the replica is fit, not if the spacing is exactly like the Cromemco part.
The Hammond chassis 1456FE1, retails around $40. In May 2024 I found various dealers with older stock for less. I found one dealer with 20-some in stock at $26 in ones, $10 in taxes and shipping, and ordered one. Took about two weeks to arrive. JS-1 vs Hammond case show the main difference is that the back is shorter.
Cherry brand chassis-mount switches vary a bit over the decades. It's about getting either the correct ones of the era, or something later that fits and looks close/exact. Ebay had two sources, one with little pips on the switch-body tops like Cromemco, one without the pips but otherwise the same. Keycaps need to look much the same, and fit the Cherry keyswitches. The discussion found some on Ebay, old-stock Cherry. Prices were about $5 a pop per keyswitch or keycap. So there's $40+ right there, with shipping from two suppliers.
Keyboards with discrete keyswitches are another world of collectable/vintage parts. My vintage Mac business introduced me into it. Turns out later, I have some Cherry switches, after pulling them out of a junked CDC disk drive tester. But their associated keycaps were white, not black.
The joystick is a used market item. As the thread discusses, and as I found independently, one buys some old joystick-based vintage R/C radio controllers, with Kraft-brand joysticks, with a silvered round "cup" around the stick. Other Kraft-brand joysticks are in black, and/or have square-shaped joysticks. They used to be $35-$50 items. I had one by happenstance, they used to turn up at hamfests. Checking ebay in June 2024, I see among several, one R/C unit with two joysticks (black square), $30 delivered. I bought that on a hunch, to see how similar the joystick parts were.
High-ohm square speakers are a bit tedious to find. The Cromemco speaker is 56 or even 100 ohm, 2.5" square speakers. Most small speakers are round not square, I've toyed with hand making some corner-mount brackets to fit those. Maybe a triangular piece X 2 or X 4? Most small replacement/hobby speakers are 8 ohm or 16 ohm. There's some 25 ohm speakers also. The higher ohm speakers were often used in wired intercoms, as both speaker and microphone. the higher impedance helped the microphone use. I had accumulated some speakers and so I found I had several low or high-ohme square and round speakers.
The Cromemco "audio amplifier" is one transistor common-collector (emitter has speaker). One can add a series resistor to an 8 ohm speaker, to provide plausible current limiting / impedance matching. My friend and old-tech Lee Hart, suggested using a Darlington transistor (two transistors in one package) to provide more gain and a lower output impedance to match a lower speaker resistance. On the visuals: Some modern speakers have big-magnets and so don't look like the originals with smaller magnets.
The 2 X 22 pin connector for the joystick cable, mates to the Cromemco D+7A card edge connector. That's an ordinary 44-pin 1/8" spacing edge connector, common in the era. I have plenty. But Cromemco had a branded blue housing over the 44 pin connector. I think someone 3D prints a replica, somewhere. (chuckle) I may take a blue bottle of laundry detergent and melt it down to make my own. I've got one of those original housings among my Cromemco boards.
The replica-thread is building a PC board, instead of using terminal strips as Cromemco did. I like terminal strips myself. Looking around eBay, I found various old-stock and used "phonoleic terminal strips", various types of construction. The Cromemco single strip has ten solder terminals, and chassis screw/rivet mounts at each end of the strip. Ebay search in June 2024, found pairs of 5-terminal strips with the same mounting hardware. I'll mount them end-to-end.
cable The JS-1 has a cable with multi-colored wires. This was a common cable scheme in the 1970's, and used in the 80's for IBM PC compatible (and CP/M compatible) serial and parallel cables. The color scheme is the familar black-brown-red-etc, like the resistor color code. To find a similar cable, I looked through my stock of old PC serial parallel cables, for something about the right diameter. I found a parallel cable (Centronic connector at one end) that was hand-produced (the connector wasn't molded on) so I could remove one connector housing and confirm it had wires of the correct colors. As my photos show, the cable exterior was almost the same color as the Cromemco JS-1 cable.
screws, feet Many of these items use screws to mount them. The Cromemco screw is 6-32 3/8" long with corresponding nut, and what's called a "flat-head slotted" head. I bought 100 screws and nuts, because spending several dollars for 100 is a better deal than spending $3 for four, five, six nuts or bolts at the local hardware store. The small rubber feet on the Cromemco are held by the four chassis screws. I had very similar feet in my parts bin.
Copyright © 2024 Herb Johnson
