A PCjr with a front panel of blinking lights is just ridiculous. :) On Oct 31, 2015 1:24 PM, "Tom Moss" <tomjmoss at googlemail.com> wrote:

Sure. The PDP8/f and PDP8/m are the well-known example. Many of the Philips P800s had optional full panels too (fortunately the ones I own do have the full panels). And there must be many more But I still claim it is difficult to add a panel to a machine that was never designed to have one. In the case of machines with optional full frontpanels the machine was designed to take a frontpanel and either to also run without it or there was some minimal panel (boot/reset/not much else) that provided enough logic that the processor didn't realise it didn't have the full panel (if you see what I mean). -tony

If you have a machine that allows for other devices to become a bus master and access memory and I/O devices (S100 does this) then it is relatively easy to make a front panel that does just that. You can then use said panel to access memory, but not, of course proceessor registers. Somebody mentioned the PCjr. Unlike the PC (and all its descendants), the PCjr doesn't have a internal DMA controller but allows for one to be added on the expansion port. As a result, a device there can take over the system bus, just what you need for a front panel. For the machines I mentioned earlier (PDP11s, VAXen, PERQs), the Unibus does of course allow for multiple bus masters. But in the case of the 11/44 and VAX11/730 main memory is not on the Unibus (which only allows for 18 bit addressing), there is an address translator which is configured by the CPU between Unibus addresses and main memory addresses. So a DMA peripheral doesn't get access to all of memory (unlilke on smaller PDP11s). And of course you wouldn't get access to processor registers, etc that way. And the PERQ doesn't allow for other bus masters at all. Memory control on that machine was designed in conjunction with the I/O system (which includes DMA controllers and the graphics system). -tony

For the sake of completeness, the other S-100 machines I can think of with a full front panel were the Ithaca Intersystems DPS-1 and some BYT-8 machines. Regards, Jeff

Although not S100, the Intellec MCS8i was a 8080 machine with a front panel. There was no hardware way to start the processor at a particular address (No logic to jam a jump instruction onto the data bus, for example). You did have a reset switch. So what you did was take the bus over from the processor (thus effectively halting the latter), toggle a jump instruction with the appropriate address into the first 3 bytes of RAM, then reset, and give the bus back to the processor. That was even the way to start the ROM monitor program -tony

Brent Hilpert wrote: Regarding Cromemco, they did sell a blinkenlights Z-1 which was essentially a Cromemco backplane and cards in an IMSAI chassis. Their ZPU processor card does have several option jumpers to make it compatible with a front panel. m

Hi Al From a panel makers point of view It would be straight forward But without at least the lamp panel its just a nice wall hanging. On 31/10/15 18:58, Al Kossow wrote: