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#108359 - 01/06/17 04:42 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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Al Kossow Offline
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Originally Posted By shattered
upd765 chip is actually available on system bus (ports 8158, 815A) and with a few hacks I forced firmware to talk to it; unsuccessfully so far -- scan ID phase fails. Maybe the FM bitrate is wrong...


the FM and MFM images use normal FDC bitrates, otherwise I couldn't have imaged them.

there is a mix of 1S FM and 2S MFM IMD files for the diagnostics

#108360 - 01/06/17 04:50 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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indeed, with rate hardcoded to 500000 and a few more hacks it manages to IPL. f.e. this is Textpack A image from bitsavers:

Code:
[:upd765] command read data cmd=06 sel=0 chrn=(0, 0, 7, 128) eot=1a gpl=07 dtl=80 rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(0, 0, 1, 128) eot=1a gpl=07 dtl=80 rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(1, 0, 1, 256) eot=0f gpl=0e dtl=ff rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(1, 0, 4, 256) eot=0f gpl=0e dtl=ff rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(1, 0, 5, 256) eot=0f gpl=0e dtl=ff rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(1, 0, 15, 256) eot=0f gpl=0e dtl=ff rate=500000
[:upd765] command read data cmd=06 sel=0 chrn=(2, 0, 1, 256) eot=0f gpl=0e dtl=ff rate=500000


Doesn't run very far though


#108368 - 01/07/17 05:48 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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With ROMs from bitsavers (apparently an older rev), CED and PDD disks boot but still complain about floppy. But hey, I got a Service Request number :-)



+


#108369 - 01/08/17 11:26 AM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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Getting there... bit 6 in floppy status port (8150) apparently reflects 'idle' status of MCU and upd765 both. Diagnostics disks are now usable and CCP/M boots. Textpack does not yet.


#108394 - 01/10/17 09:33 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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Textpack 1 probably crashes because 128KB is not enough memory for it, but simply mapping more memory does not make it work and diags don't detect extra memory as well... So instead, here's how 66-line display is supposed to look. Only works with "new" firmware:


#110630 - 08/20/17 04:28 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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https://www.youtube.com/watch?v=S5pZ9mB1mGg -- no new progress to report, just shows diag disks booting in 0.188 and doing their stuff

#112719 - 02/21/18 09:01 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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Originally Posted by shattered

Self-test on this machine is very, very paranoid -- I think I've found a emulation bug in i8255.cpp smile

Code
@@ -473,6 +473,11 @@ uint8_t i8255_device::read_pc()
        {
                // read data from port
                data |= m_in_pc_cb(0) & mask;
+               if (port_c_upper_mode() == MODE_OUTPUT)
+               {
+                       // read data from output latch
+                       data |= m_output[PORT_C] & mask;
+               }
        }

        return data;


This should probably be "data |= m_output[PORT_C] & 0xf0;". That way, it doesn't break pasopia7 and pc9801 drivers like the "& mask" does smile -- https://github.com/mamedev/mame/pull/1950

#112720 - 02/21/18 09:19 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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Edstrom Offline
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Hmm, it isn't just a missing set of paranthesis?

#112721 - 02/21/18 09:25 PM Re: IBM Displaywriter (1980) WIP [Re: shattered]  
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shattered Offline
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at this point, mask is 0x0f or narrower, and high bits are not set at all -> breakage ensues.

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