For Sale: HP-71B MultiMod ROM Emulator

[mfleming]

(03-10-2021 01:48 AM)rprosperi Wrote:  Suggestion:

Please post a link (e.g. Amazon, eBay, etc.) for a USB cable that is the proper type, not needing special 'anything', just connect and go.

Folks that like to dabble with such things will ignore it and likely comment how 'obvious' this should be. I'll live with the comments, and in fact, I'm already over them.

Thanks Mark.

Hi Bob,

Those little cables are so ubiquitous (in electronics anyway) that it's like asking for a recommendation for a good screwdriver. I'll give you my own criteria for picking a cable and the one I currently use.

First, go for one with an FTDI chip. There are other perfectly good companies that make their own USB to serial chips, but FTDI has a broad portfolio and experience in the field. If imitation is the sincerest form of flattery, then FTDI is also the supplier with the most number of knockoff chips.

Get a cable or interface with all the signals, and make sure those signals are labeled! Those four-wire cables only provide transmit and receive, but if you use Arduino boards or other electronics, you're likely to need some of the hardware handshake signals. The Mench board for instance implements a full hardware serial interface where just Rx/Tx won't do.

Get one that supports multiple voltage levels. There are still applications that need 5V interfaces, but 3.3V is increasingly becoming the norm. It's best to have one board that can be strapped for your target voltage.

A final nice-to-have would be a configuration that lets you use your own USB cable. Nothing worse than being tethered to your PC by a much-too-short cable.

The one I'm currently using is the DSD Tech SH-U09C2 USB to TTL Adapter available from Amazon. You'll need an appropriate USB cable extender with an A Male to A Female connectors of whatever length you choose. There's a plastic case to prevent gefingerpoken und mittengrabben damage, and it can be removed to access less commonly used serial signals. It can also be strapped for 5V, 3.3V, and 1.8V operation. The FTDI chip itself can be configured for things like complemented signal levels as needed by the Sharp PC-G850VS. Well worth the twelve bucks (plus cable).

One last suggestion; don't buy anything under $10, you'll just end up throwing it away.
~Mark