Tandy 200 RAM - Revision history

Sadolph: /* Bank To Bank Copy */

2009-03-19T22:19:53Z

Bank To Bank Copy

← Older revision		Revision as of 15:19, 19 March 2009
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	need about the directories, then do the byte copies.		need about the directories, then do the byte copies.

	There is a routine at 2FC5 that copies B bytes from (HL) in source to		There is a routine at 2FC5 that copies BC bytes from (HL) in source to
	(DE) in target-- you could use that to copy things to ALTLCD in the		(DE) in target-- you could use that to copy things to ALTLCD in the
	ram banks-- then you have your environment prepped for doing the bank		ram banks-- then you have your environment prepped for doing the bank

Sadolph: /* Remote block copy code at 2FC5 */

2009-03-19T22:19:01Z

Remote block copy code at 2FC5

← Older revision		Revision as of 15:19, 19 March 2009
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	== Remote block copy code at 2FC5 ==		== Remote block copy code at 2FC5 ==
	; this routine copies B bytes from (HL) in source to (DE) in target		; this routine copies BC bytes from (HL) in source to (DE) in target
	; enter with source RAM visible		; enter with source RAM visible

Sadolph: /* Bank Selection */

2009-03-19T18:21:18Z

Bank Selection

← Older revision		Revision as of 11:21, 19 March 2009
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	In the T200 memory map, there are 6 defined blocks - 3 ROM and 3 RAM. Bank selection is accomplished by writing to IO port D8 (216). The current setting of the bank selection may be read back from D8 also.		In the T200 memory map, there are 6 defined blocks - 3 ROM and 3 RAM. Bank selection is accomplished by writing to IO port D8 (216). The current setting of the bank selection may be read back from D8 also.

	Bit 1,0 --> selection of ROM bank (0000-9FFF or 0000-7FFF)		Bit 1,0 --> selection of ROM bank (0000-9FFF or 0000-7FFF)
	00 = main ROM (40k)		00 = main ROM (40k)
	01 = multiplan (32k)		01 = multiplan (32k)
	10 = option ROM (if installed)		10 = option ROM (if installed)
			Bit 3,2 --> selection of RAM bank (A000-FFFF)
	Bit 3,2 --> selection of RAM bank (A000-FFFF)		00 = bank 1
	00 = bank 1		01 = bank 2 (if installed)
	01 = bank 2 (if installed)		10 = bank 3 (if installed)
	10 = bank 3 (if installed)

	Register D8 can be written at any time, with catastrophic results if not done correctly!		Register D8 can be written at any time, with catastrophic results if not done correctly!

Sadolph: /* Bank To Bank Copy */

2009-03-19T17:17:00Z

Bank To Bank Copy

@@ Line 36: / Line 36: @@
 ram banks-- then you have your environment prepped for doing the bank
 to bank copy from RAM.
 == ALTLCD ==

Jhoger: /* Bank To Bank Copy */

2009-03-19T14:51:21Z

Bank To Bank Copy

← Older revision		Revision as of 07:51, 19 March 2009
Line 23:		Line 23:
	The T200 ROM provides a routine to perform a bank-to-bank memory copy.		The T200 ROM provides a routine to perform a bank-to-bank memory copy.

	To accomplish this, the T200 uses spare memory in the ~~timer chip~~ to		To accomplish this, the T200 uses spare memory in the [[Tandy 200 Timer]] to
	store the source and destination ram banks.		store the source and destination ram banks.

Jhoger: /* Bank Selection */

2009-03-19T14:35:34Z

Bank Selection

← Older revision		Revision as of 07:35, 19 March 2009
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	Register D8 can be written at any time, with catastrophic results if not done correctly!		Register D8 can be written at any time, with catastrophic results if not done correctly!

	~~I believe there are rom routines for bank to bank copy or reads, but I can't find them currently.~~

	== Bank To Bank Copy ==		== Bank To Bank Copy ==

Jhoger: /* Bank Switch */

2009-03-19T14:35:09Z

Bank Switch

← Older revision		Revision as of 07:35, 19 March 2009
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	This page captures some useful information for programming with T200 RAM.		This page captures some useful information for programming with T200 RAM.

	== Bank ~~Switch~~ ==		== Bank Selection ==

	T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.		T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.

Jhoger: /* T200 RAM selection */

2009-03-19T14:34:04Z

T200 RAM selection

← Older revision		Revision as of 07:34, 19 March 2009
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	This page captures some useful information for programming with T200 RAM.		This page captures some useful information for programming with T200 RAM.

	== ~~T200 RAM selection~~ ==		== Bank Switch ==

	T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.		T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.

99.6.119.22 at 14:31, 19 March 2009

2009-03-19T14:31:25Z

← Older revision		Revision as of 07:31, 19 March 2009
Line 1:		Line 1:
	This page captures some useful information for programming with T200 RAM.		This page captures some useful information for programming with T200 RAM.

	T200 RAM selection		== T200 RAM selection ==
	~~------------------~~

	T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.		T200 RAM is always 24k blocks, from A000 to FFFF. There can be any number of banks from 1 to 3.
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	I believe there are rom routines for bank to bank copy or reads, but I can't find them currently.		I believe there are rom routines for bank to bank copy or reads, but I can't find them currently.

			== Bank To Bank Copy ==

	~~ALTLCD~~		The T200 ROM provides a routine to perform a bank-to-bank memory copy.
	------
			To accomplish this, the T200 uses spare memory in the timer chip to
			store the source and destination ram banks.

			Then there are a set of rom routines that do the bank to bank copies.

			So, you can imagine then how this works - you store the critical data
			somewhere accessible always, then bank switch getting all the info you
			need about the directories, then do the byte copies.

			There is a routine at 2FC5 that copies B bytes from (HL) in source to
			(DE) in target-- you could use that to copy things to ALTLCD in the
			ram banks-- then you have your environment prepped for doing the bank
			to bank copy from RAM.

			== ALTLCD ==

	ALTLCD exists in all 3 RAM banks, and is 640 bytes long, running from F7B0 (63408) to FA2F (64047).		ALTLCD exists in all 3 RAM banks, and is 640 bytes long, running from F7B0 (63408) to FA2F (64047).

	[[Category:Model T Developer Reference]]		[[Category:Model T Developer Reference]]

Jhoger at 03:11, 19 March 2009

2009-03-19T03:11:59Z

← Older revision		Revision as of 20:11, 18 March 2009
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	ALTLCD exists in all 3 RAM banks, and is 640 bytes long, running from F7B0 (63408) to FA2F (64047).		ALTLCD exists in all 3 RAM banks, and is 640 bytes long, running from F7B0 (63408) to FA2F (64047).

			[[Category:Model T Developer Reference]]