Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.10 $; site trsvax Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!convex!trsvax!uhclem From: uhclem@trsvax Newsgroups: net.micro.trs-80 Subject: Re: Again: What makes the Model 4 work? Message-ID: <70700054@trsvax> Date: Wed, 27-Nov-85 10:36:00 EST Article-I.D.: trsvax.70700054 Posted: Wed Nov 27 10:36:00 1985 Date-Received: Sat, 30-Nov-85 06:45:48 EST References: <408@houem.UUCP> Lines: 72 Nf-ID: #R:houem.UUCP:408:trsvax:70700054:000:3561 Nf-From: trsvax!uhclem Nov 27 09:36:00 1985 <"What do you mean 'It's in Reserved for future use phase'? Oh, its SCSI."> >"OUT 132,4" puts up an 80x24 screen (at reduced brightness), with That is right. I take it you have one of the older model units, and when you changed the screen clocking to the higher rate, the RFI torroids clip the white signal more obviously. If this bothers you, you can fix it real fast by pulling these out, but beware: on some units you will start picking up herringbone patterns and other harmonic crud in your video. In the later units they fixed this, and there may be a TCO available to cover it. Check with your local Service shop. >garbage in the bottom half and the lines out of alignment. "OUT Also right. The old Model IV ROM only cleared the 1K that was used in Model III mode, and it was the responsibility of any Model 4 operating system to clear the other half. You are just seeing uninitialized video RAM. As to the alignment, the Model IV ROM thinks that every 64th byte is the start of a new line, not every 80th, so things do get messed up it you try to use the ROM video drivers in 80 column mode. >Is there a noise-maker in the Model 4? I tried "OUT 144,everything" The port that I gave you is correct, but it finally registered that you have a diskless system. Look at the back (not the bottom) and see if the RS-232 port comes out of the machine at the seam between the top and bottom of the machine. If it is not there, then look underneath and see if it is in the second row, center hole on the bottom. If the RS-232 port is on the bottom and the machine has no disk drives, then it will not have a bell. It was decided (not by me, so no flames please) that if the machine could not run Model IV software (no drives), and no Model III software knew about the bell, then leaving that part off would be a nice way to cost-reduce the drive-less unit. If the RS-232 port comes out the back, then you get one no matter what, since the speaker is now built onto the motherboard. (The sound stuff gets added with the first floppy drive on the older units.) The schematic for the sound board (for machines with RS-232 port coming out the bottom) is on Page 22 of the Model 4 Technical Reference and is real big: |:(?) 4 +-----------------------------+--- +----O----+ | ^+5 D0 2| P | +--------------------+ 3>--------------|D U1 | | R1 1.8K / BLK | 74LS74 | +--\/\/\/---+ ^/ E SEN 3| | | / \ Q1=2N3906 1>--------------| ~Q|------\/\/\/---+---B( Q1 ) WHT | C |6 R2 3.6K \ /\C +----O----+ -- \__/\/\/\/--->QMB6<--+ |1 R3 120 OHM | | VCC (14)=+5 GND 2>----+---+5---------+ VDD (7)=GND | QMB6 is one of those piezo-speakers --- C1 .1uf without the tone generation circuitry. --- Don't use a Sonalert as you will always get | the same pitch. 4>----+---GND So you can build one if you find you don't have, or you might order a finished one from National Parts. With that part-count, it can't be too expensive. "Thank you, Uh Clem." Frank Durda IV @ "The crime of copy-protecting bears bitter customers. The Lawyer knows."(tm)