TIM-1 design

[MrBiff]

Hi,

This is my first post. As a vintage computer collector I find the eBay listings too expensive.
Instead, I am building my SBC designs.
For this forum, I submit my latest design, the TIM-1.
It differs from the original by replacing the 6530 with a 6532 and EEPROM.
The assembly code had to be modified as well.
I thank the 6502.org for providing the information and tools to make this possible.

Cheers.

[BigEd]

Very nice - and welcome!

[ttlworks]

Welcome, reminds me to the Elektor Junior Computer which also had a 6532 and an EPROM (instead of the 6530).

[Dr Jefyll]

Nice work, MrBiff! And welcome.

I'm embarrassed to say I didn't know what a TIM-1 is, although the KIM-1 is very familiar. But this item on http://www.old-computers.com set me straight.

Quote:

The TIM (Terminal Interface Monitor) was a MOS Technology Inc's build-it-yourself 6502 development system that was launched before the KIM-1.

When a computer fan ordered a TIM from MOS Technology in Norristown, Pennsylvania, he got a MCS6530-004 (1k TIM monitor program in ROM), and a manual (15 sheets of 11x17 folded & stapled in the middle) containing a suggested schematic, the TIM monitor commands, and listing.

Mike N has posted a scan of that manual here (thanks, Mike!). The suggested schematic (below) is fairly minimal -- charming, I'd say!

-- Jeff

[fhw72]

Thanks for the schematic... maybe I should finally do something with my bunch of TIM chips!?

[ttlworks]

fhw72 wrote:

maybe I should finally do something with my bunch of TIM chips!?

Hmm... like talking a vintage computer collector into trading these 15 chips for a new car ?
Not a big car, just kidding.

[HansO]

The Jolt and the Super Jolt were also based on the TIM-1

More TIM-1 info here: http://retro.hansotten.nl/6502-sbc/tim-6530-004/

[Michael]

Very nice, Peter. Would you consider sharing your version schematic and source code, please?

Cheerful regards, Mike

[MrBiff]

Hi,
In response to an information request, I decided to respin my TIM-2.
I have attached the schematic PDF and the tested assembly code.
Note, the schematic indicates Max232 but I have changed this to the Max3232.
Note: for some reason, the decoupling capacitor for the 6116 RAM is missing on the PCB despite that the schematic has it.
This does not prevent the system from working
Cheers.

[Michael]

Thank you, Peter. Looks like you shaved one IC off the BOM, too. Bravo!

Cheerful regards, Mike, K8LH

[BigDumbDinosaur]

MrBiff wrote:

Note, the schematic indicates Max232 but I have changed this to the Max3232.

Any particular reason?

Quote:

Note: for some reason, the decoupling capacitor for the 6116 RAM is missing on the PCB despite that the schematic has it.

In the future, please consider posting your schematics in monochrome.

[MrBiff]

The serial connection works ok if I use a Max3232 serial to TTL module which has the Max3232.
That connects to the 4 post header next to the Max232.
For some reason, which I have not figured out yet, the on-board Max 232 circuit does not always work.

[BigDumbDinosaur]

MrBiff wrote:

The serial connection works ok if I use a Max3232 serial to TTL module which has the Max3232.
That connects to the 4 post header next to the Max232.
For some reason, which I have not figured out yet, the on-board Max 232 circuit does not always work.

I don't know why it wouldn't, unless you are using the wrong charge pump capacitors. The MAX232 and siblings all accept TTL-level inputs, so that should be an issue with an NMOS UART.

[MrBiff]

I found my problem with the RS-232 circuit.
The culprit is an erroneous symbol provided by the user community in EasyEDA.
I have re-spun the PCB and I am waiting for delivery.