towson%amsaa@sri-unix.UUCP (12/16/83)
From: David Towson (CSD) <towson@amsaa> Tim - Unless your system has a pretty fancy interrupt handler, it seems unlikely that typeahead will work while ANY program is being loaded from a floppy, as interrupts from the keyboard would interfere with the operation of the disk controller (if it uses interrupts) or of the disk-reading software (if the disk controller doesn't use interrupts). A fancy interrupt handler could determine the source of an interrupt (given proper hardware support), but really rapid typing would still screw things up occasionally unless you have a really fast processor. I don't see how a particular program could have a unique effect on this situation while it is being loaded (that is, before it even starts to execute). Are you sure you have the story straight? Dave
Fat.Tag@SU-SIERRA.ARPA (12/16/83)
From: Tim Gonsalves <Fat.Tag@SU-SIERRA.ARPA>
The Z-100 has an interrupt controller chip that multiplexes interrupts from
several devices into the 8088 processor. Thus the software can indeed
determine the source of the interrupt and handle it appropriately and the
bios is written to allow interrupts during interrupts and so on. The
keyboard has a separate processor (8041) for decoding keys. There is a
fast repeat feature with which one key repeats at 22/second. Even at this
rate, whilst loading a program everything works fine.
>From one of the replies to my query I've learnt that FW does indeed flush
the typeahead buffer when it starts up because it provides some typeahead
on its own for machines that do not have the builtin capability. Likewise,
when quitting, it reads some characters beyond the quit commnd into its
buffer before recognizing the quit command. These characters get thrown
away.
Tim
-------Fat.Tag@SU-SIERRA.ARPA (12/20/83)
From: Tim Gonsalves <Fat.Tag@SU-SIERRA.ARPA> I have a problem with the Final Word on a H/Z-100 with Z-DOS: any characters typed whilst FW is being loaded from the floppy get lost. Likewise, there is some lossage during quitting. The Z-100 has an interrupt-driven keyboard handler with an 80-character buffer. I have not noticed any loss of typeahead with any other software (and, I use this feature a lot because of the speed of floppies). Has anyone else noticed this problem on this or other similar machines? Any fixes for it? I wrote to Mark of the Unicorn describing this behaviour. A support person there phoned me today to try to help (very decent of them). Unfortunately, she did not appear to understand what typeahead means. After I spent some time explaining, she informed me that no microcomputer software allows typeahead during program loading (except possibly some Zenith-specific utilities), and she could see no reason why anyone would want to typeahead anyway! Further, since noone else had complained to MoU about FW losing typeahead, it is apparently not likely that MoU will fix the problem. Being many years since I've used a machine that did not support typeahead, any help will be appreciated. Tim Gonsalves@SU-Sierra.Arpa -------