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Tea v0.09

Following Eurovision, I noticed that Tea was drawing a broken grid, something like this...
A messed up grid
A messed up grid.

This is happening because the day change was happening at midnight, but the schedule change appears to happen around 5am. As a result of this, the hour offsets weren't matching the day.
In order to work around this, I've added a fudge that will simply subtract 1 from "what day is today" if it's before 5am.
This code has been tested in theory, but not in reality. It's a workday tomorrow so please excuse me not wanting to stay up to 1am. In addition, the actual time of the schedule change is not known, I'm just guessing that it is 5am as that's when the daily schedule appears to start/end. Hopefully you'll all be asleep then so that won't be a problem. ☺

Download tea_0-09.zip (385.5K)
For RISC OS machines.

 

Complexity

While I was sitting outside a couple of days ago, I was idly looking at the Roland E-15 Service Manual, and what caught my attention was this.
Roland E-15 block diagram
Roland E-15 block diagram.

It's a bit hard to see due to being shrunk to fit, so allow me to explain that the keyboard and front panel controls (the right side of the diagram) are fed in a 68HC11 processor. It looks like the only connection between this and an H8 processor is via a MIDI switch, so it appears as if the actual keyboard and/or the front panel may translate what is happening into MIDI commands, that are then interpreted by the rest of the keyboard. That seems to be a bit of an odd way to do it, but okay...

I finally found a Service Manual for my E-16 and there are way more differences than a simple change in model number might suggest. I mean, you'd think the E-16 was a later or slightly better E-15, wouldn't you?

The E-15 has a 24SC201 sound generator hooked to two 8Mbit ROMs (that's 2MBytes), the 6811 (with an 8MHz crystal) controlling all the pokey-proddy parts, and passing MIDI data in serial format to an H8 (taking its clock from a 20MHz crystal) to perform the actual sound synthesis. MIDI out comes from the 6811, so all of the drums and such are being handled by the eight bit processor. It is, logically, two separate units in one box - the keyboard/interface part, and the sound synthesis part.

Here's the E-16.

Roland E-16 block diagram
Roland E-16 block diagram.

This is much simpler, and no longer splits the unit into two logical sections. Everything is now handled by an H8 processor clocked from a 20MHz crystal. It shares a full address and data bus with a GP4 sound generator (a Roland TC6116AF, a fairly widespread wavetable synth chip). The wave ROM is an 8Mbit part (1MByte), despite it seeming as if this device offers more voices.

 

This is all a bit academic as I don't use my Roland much. The primary reasons are that it uses serial MIDI which is a pain with modern machines; plus it is a rather peculiar (non-compliant) implementation of MIDI. Much easier to plug in my (USB) Yamaha that just works. But it was interesting to look to see how the devices fit together inside.

For comparison, here's the Yamaha. Sorry about the black bits. This is the sort of thing that happens when you use the simplistic photo editor on a mobile phone to manipulate screenshots...

Yamaha PSR E333 block diagram
Yamaha PSR E333 block diagram.

 

 

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Last read at 11:47 on 2024/05/30.

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