No idea. I would buy an XT on eBay. GL & HF!

Retro hardware is not always a viable solution for all.

and the ones that do emulate an XT/AT that slow generally aren't stable for industrial use and don't have serial passthrough.

You might need to be aware that the g in Vogons stands for games and for radio signal stuff you won't get much help for that at all here.

The practical upper bound on the serial port speed is not dependent on the overall system speed so much as it is on the quality of the UARTs used in the serial port equipment, although both ARE relevant. Common UARTs in the 1980s were typically usable up to a maximum of 19200 baud in systems from that era when connected to external devices. So you can probably use any serial port on any machine for your purpose as long as you cap the serial port baud rate at 9600 or 4800 baud. If that proves to be too fast, lower it still further (2400, 1200 or even 300 baud).

If the issue is having to run DOS software to program the radio, then you might consider looking for a machine with a 32-bit version of Windows with RS-232 serial port hardware as that should be capable of running your 16-bit DOS program. The properties dialog box for the serial port in Windows Device Manager should allow you to lower the serial port baud rate to whatever baud rate you need for your external circuit as well as set other parameters such as parity, start/stop bits, etc. Obviously, you would be better off it you can test your software on a 32-bit Windows system before you spend any money in order to make sure that it runs properly. For example, your program might require graphical modes that more recent graphic adapters support poorly or don't support at all.

marius67 wrote:

Hello […]
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Hello

I need to emulate a DOS PC XT or AT with a max of 8 MHz. (can also be slower but not faster)

What I like to do is some programming of a Radio over the serial interface. I have a circuit wich changes the RS232-TTL signals vice versa but the signals may not to be sent over the serial interface faster than on a AT with 8 MHz.
Is that possible with DOSBOX or do I need to look for an antique PC for that?

Any help is appreciated,
Marius

On my old 8086 and XT systems that had a "Turbo Button" on the front. Pushing it forced the CPU into virtual 8086 "real mode". Maybe it's an config option in the DosBOX cfg/ini files?

leileilol wrote:

... and for radio signal stuff you won't get much help for that at all here.

*KOFF*

*raises hand*

It's mostly limited to WiFi, 900MHz, and ISM bands, but I've done radio work professionally.

DOSBox might work if you decrease the emulated cycles far enough. But there have been many threads here in the past in which people have attempted to use the serial port passthrough of DOSBox with older applications, and you may not be successful even if you decrease the speed of DOSBox as far as it goes. To echo the above, reliable serial port emulation for radio signal programs and the like is not one of the goals of DOSBox.

ElectricMonk wrote:

On my old 8086 and XT systems that had a "Turbo Button" on the front. Pushing it forced the CPU into virtual 8086 "real mode". Maybe it's an config option in the DosBOX cfg/ini files?

What are you babbling about? Virtual real mode was only introduced with the 386. The only thing an XT system might have had would be a button to change the clock multiplier.

Jorpho wrote:

DOSBox might work if you decrease the emulated cycles far enough. But there have been many threads here in the past in which people have attempted to use the serial port passthrough of DOSBox with older applications, and you may not be successful even if you decrease the speed of DOSBox as far as it goes. To echo the above, reliable serial port emulation for radio signal programs and the like is not one of the goals of DOSBox.

ElectricMonk wrote:

On my old 8086 and XT systems that had a "Turbo Button" on the front. Pushing it forced the CPU into virtual 8086 "real mode". Maybe it's an config option in the DosBOX cfg/ini files?

What are you babbling about? Virtual real mode was only introduced with the 386. The only thing an XT system might have had would be a button to change the clock multiplier.

Yeah, I was wrong about it being on my NCR XT. For some reason, I'd swear it was on my 286-12, though. But I'm probably wrong about that too, oh guru of the obsolete gear. :kowtows: