Twospruces
Veteran Member
I have 2 machines displaying very different speed capabilities on RS-232.
1) Z-171, 80C88 4.7MHz, 8250 UART with 1.8432MHz crystal
--> works well at 9600baud, but receiver cannot keep up at 19200 baud
2) Sharp PC-6220, 80286 6/12MHz, unknown serial hardware
--> supports 115200 baud
obviously a part of this is processor and clock rate, but I am wondering, were all XT 8088 machines limited to 9600 baud? This seems really slow.
I feel like the Z-171 has some impairment relative to a normal XT. Since the Z-171 actually has a slower benchmark relative to XT, I guess there must be some interrupt consuming cycles (like the video subsystem) and that ultimately limits how fast the CPU can serve the 8250 UART.
Anyone have any thoughts on this? thanks.
1) Z-171, 80C88 4.7MHz, 8250 UART with 1.8432MHz crystal
--> works well at 9600baud, but receiver cannot keep up at 19200 baud
2) Sharp PC-6220, 80286 6/12MHz, unknown serial hardware
--> supports 115200 baud
obviously a part of this is processor and clock rate, but I am wondering, were all XT 8088 machines limited to 9600 baud? This seems really slow.
I feel like the Z-171 has some impairment relative to a normal XT. Since the Z-171 actually has a slower benchmark relative to XT, I guess there must be some interrupt consuming cycles (like the video subsystem) and that ultimately limits how fast the CPU can serve the 8250 UART.
Anyone have any thoughts on this? thanks.