![[assembled badge]](badge_revc_built.jpg){kind=icon}
Last updated June 3 2025 Edited by Herb Johnson, (c) Herb Johnson Contact Herb at www.retrotechnology.com, an email address is on that page.
Quick Web page on Lee Hart 2024-forward COSMAC 1802 Vintage Badge kit, Revisions A, B and C, with manuals. All photos by Herb Johnson.
Check Lee Hart's Web site for purchase of the 1802 Badge kit.
component side Rev B C PC board
solder side Rev B C PC board
assembled Rev B C board
detail of USB/TTL dongle to show wiring back to badge
Rev C manual & schematic 10 Feb 2025
Rev B manual & schematic 30 Mar 2025
"[The differences between Rev B and Rev C are: a) I added a slot at the bottom edge for the battery holder wires (so they can be soldered on top but routed thru the slot to the battery holder on the back). And b) more space around the on/off switch (because the metal tabs of the switch could short to traces on the top of the board)." - Lee Hart
Lee Hart produced a prototype Rev A Badge. Here is a Rev A assembly manual, Nov 27 2024. The Rev A has two 74HC573 ICs and may not support RAM, although there's a RAM location on the PC board. Turns out there's a timing issue, writing to RAM takes the same timing as writing to the display. (I'm unsure what the consequences are. - Herb). A number of them were produced in 2024 and sold through 2025. Rev B and C have a 74HC573 and a 74HC541 and support 8K 300mil RAM (not 32K) without timing issues.
David Madole provided ROM-based codes for a user-modified displayed message as held in 1802 spare registers (no RAM used). Codes more recent might be found on cosmacelf groups.io discussion list posts. Here's the groups.io thread from early Sept 2024. Search the list for more recent discussion, code, fixes.
Meanwhile, here's the 2024 Madole github site for this Namebadge code. It supports a serial terminal or pushbuttons to enter a message; no RAM is needed, the message is held in 1802 registers.
While David advises to use the ASM/02 assembler, the code will assemble under "my" A18 cross assembler if you
add a list of register equates (r0 equ 0, etc.) - Herb
Oct 21 2024:I (Herb Johnson) produced some simplified ROM-only code for the 'badge. Here's two versions. These rely on a ROM-programmed message, to demonstrate how to access the display. So, no need to poke at EF buttons to enter message, no message lost when batteries fall out, and no cramming registers to hold the message. One version is a 8-char message only, no message scrolling, and so relatively simple code. The other version scrolls a longer message. Neither include serial line support (no terminal) or read the buttons (EF support). Either version can be fit in one ROM page (uses two now from convenience) and only needs four 1802 registers. There's no serial support or button support - nothing to tell the badge! ;)
- Herb Johnson
This page is copyright Herb Johnson (c) 2025. Some content on this page, belongs to the authors so named, and is used with their permission. Contact Herb at www.retrotechnology.com, an email address is available on that page..
