Hi,

I try to use the internal counter/timer 1 of the Z280 as the baudrate
generator for the internal uart. So far the timer 1 is not running.
I see the output of the counter/timer 1 is set to one, but the output
doesn't toggle.

My timer code is below

ld hl, 14 ; timer constant
ld c, $ea ; counter 1 time constant
outw
ld a, $88 ; counter continuous, output enabled,
; timer
out ($e8), a ; counter 1 configuration
ld a, $c0 ; enable, software gate set
out ($e9), a ;

I can read the all the counter/timer registers and they ar set to the
correct values. When I read the count-time register, it is always set
to 14, never changing. I even tried to use the counter/
timer 1 as a counter, with a an square wave signal at the input of the
counter, but this is also not working.

I bought five Z280 from utsource years ago. Two of them show a very
weird behavior. Address and control pins toggle, but the Z280 program is
not running as it should. The other three Z280 run, but the
counter/timer 1 does not work at all.
Maybe I bought an batch of Z280

Is there a undocumented bit in one of the registers of the Z280, which
has to be set, in order to get the counter/timer working, or has anybody succeeded using the counter/timer 1 of the Z280.

Regards,
Robert

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Am 07.08.2023 um 15:47 schrieb Robert:

I try to use the internal counter/timer 1 of the Z280 as the baudrate generator for the internal uart. So far the timer 1 is not running.
I see the output of the counter/timer 1 is set to one, but the output
doesn't toggle.

My timer code is below

ld hl, 14 ; timer constant
ld c, $ea ; counter 1 time constant
outw
ld a, $88 ; counter continuous, output enabled,
; timer
out ($e8), a ; counter 1 configuration
ld a, $c0 ; enable, software gate set
out ($e9), a ;

When I used the Z280 decades ago, I set the CS1 register to E0h, not C0h.

Don't have the manual at hand to look up what that means...

Tilmann

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Am 07.08.2023 um 15:47 schrieb Robert:

Hi,

I try to use the internal counter/timer 1 of the Z280 as the baudrate generator for the internal uart. So far the timer 1 is not running.
I see the output of the counter/timer 1 is set to one, but the output
doesn't toggle.

I can't help but there is a manual:

https://oldcomputers-ddns.org/public/pub/rechner/zilog/z280/manual/index.html

--
-- Fritz

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Am 08.08.2023 um 08:33 schrieb Tilmann Reh:

When I used the Z280 decades ago, I set the CS1 register to E0h, not C0h.

Don't have the manual at hand to look up what that means...

Following the manual linked by Fritz, that makes the difference.

Bit 5 is the Trigger Bit ("TG"), which needs to be set from 0 to 1 to
start the counter/timer. See page 9-7 of the manual, last paragraph.

Tilmann

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On 8/8/23 17:07, Tilmann Reh wrote:

Am 08.08.2023 um 08:33 schrieb Tilmann Reh:

When I used the Z280 decades ago, I set the CS1 register to E0h, not C0h.

Don't have the manual at hand to look up what that means...

Following the manual linked by Fritz, that makes the difference.

Bit 5 is the Trigger Bit ("TG"), which needs to be set from 0 to 1 to
start the counter/timer. See page 9-7 of the manual, last paragraph.

Tilmann

@ Fritz and Tilmann

Thanks for the help
The timer 1 is now working

Robert

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