F256K - Revision history

PJW at 02:43, 5 July 2023

2023-07-05T02:43:06Z

2023-07-03T16:03:17Z

2023-07-03T15:57:55Z

2023-06-27T07:05:17Z

‎Memory

2023-06-27T07:05:02Z

‎Memory

2023-06-27T07:03:06Z

‎Memory

2023-06-26T16:16:47Z

‎Keyboard

2023-06-26T16:09:51Z

‎Boot

2023-06-26T06:47:03Z

‎Memory

2023-06-26T06:27:02Z

‎Ports and connectors

@@ Line 7: / Line 7: @@
 * 1x IEC Port to interface to Commodore Drives
 * A few sound chips: SID, PSG/SN76489, OPL3
 It shares many similarities to the [[F256JR]] and programs can in many cases run straightforwardly on both.

@@ Line 155: / Line 155: @@
 STA MMU_MEM_CTRL  ; disable mmu edit, use mmu lut 0</nowiki>
 to commit the changes and enable use of the updated MLUT 0.
 = Keyboard =

@@ Line 6: / Line 6: @@
 * Port for connecting FNX4N4S, which can be used to connect Atari-Style Joysticks or NES/SNES gamepads
 * 1x IEC Port to interface to Commodore Drives
-* SID sound chip
+* A few sound chips: SID, PSG/SN76489, OPL3
 It shares many similarities to the [[F256JR]] and programs can in many cases run straightforwardly on both.

@@ Line 153: / Line 153: @@
 LDA MMU_MEM_CTRL
 AND #~(MMU_EDIT_EN)
-STA MMU_MEM_CTRL  ; disable mmu edit, use mmu lut 0
+STA MMU_MEM_CTRL  ; disable mmu edit, use mmu lut 0</nowiki>
 to commit the changes and enable use of the updated MLUT 0.

← Older revision		Revision as of 07:05, 27 June 2023
Line 148:		Line 148:

	where MMU_MEM_BANK_0, 1, 2, are specially mapped at addresses $0008, $0009, and so on. In this example code, the accumulator stores the bank number of device memory, and that value is written to the corresponding register. Write higher values to map later regions of device memory.		where MMU_MEM_BANK_0, 1, 2, are specially mapped at addresses $0008, $0009, and so on. In this example code, the accumulator stores the bank number of device memory, and that value is written to the corresponding register. Write higher values to map later regions of device memory.
		+
		+	Finally, use
		+	<nowiki>
		+	LDA MMU_MEM_CTRL
		+	AND #~(MMU_EDIT_EN)
		+	STA MMU_MEM_CTRL ; disable mmu edit, use mmu lut 0
		+	</nowiki>
		+	to commit the changes and enable use of the updated MLUT 0.

	= Keyboard =		= Keyboard =

← Older revision		Revision as of 07:03, 27 June 2023
Line 127:		Line 127:

	As for where a bank of CPU address space can map to: programs can map a bank to any of RAM, flash or expansion memory.		As for where a bank of CPU address space can map to: programs can map a bank to any of RAM, flash or expansion memory.
		+
		+	An example of a straightforward mapping is to simply map the CPU address space linearly to the first 64KB of RAM.
		+	<nowiki>
		+	LDA #$00
		+	STA MMU_MEM_BANK_0 ; map $000000 to bank 0
		+	INA
		+	STA MMU_MEM_BANK_1 ; map $002000 to bank 1
		+	INA
		+	STA MMU_MEM_BANK_2 ; map $004000 to bank 2
		+	INA
		+	STA MMU_MEM_BANK_3 ; map $006000 to bank 3
		+	INA
		+	STA MMU_MEM_BANK_4 ; map $008000 to bank 4
		+	INA
		+	STA MMU_MEM_BANK_5 ; map $00a000 to bank 5
		+	INA
		+	STA MMU_MEM_BANK_6 ; map $00c000 to bank 6
		+	INA
		+	STA MMU_MEM_BANK_7 ; map $00e000 to bank 7</nowiki>
		+
		+	where MMU_MEM_BANK_0, 1, 2, are specially mapped at addresses $0008, $0009, and so on. In this example code, the accumulator stores the bank number of device memory, and that value is written to the corresponding register. Write higher values to map later regions of device memory.

	= Keyboard =		= Keyboard =

@@ Line 132: / Line 132: @@
 There are two ways for programs to interact with the keyboard:
-* '''Using the kernel''', where the exact mechanism depends on the kernel involved
+* '''Using the kernel''', where the exact mechanism depends on the kernel involved; this can be through an environment like SuperBASIC that talks to the kernel
 * '''Directly with the device''', using memory mappings.

@@ Line 69: / Line 69: @@
 Switching DIP1 to 'on' is useful for developer convenience and testing code. For those using the machine outside of a development-style environment, it's more likely the switch will be 'off'.
-The ''Boot from RAM'' and ''Boot from Flash'' options in uploader tools such as [https://github.com/pweingar/FoenixMgr FoenixMgr] or [https://github.com/clandrew/F256Uploader F256 Uploader] are unrelated to the "Boot from RAM" DIP switch:
+The ''Boot from RAM'' and ''Boot from flash'' options in uploader tools such as [https://github.com/pweingar/FoenixMgr FoenixMgr] or [https://github.com/clandrew/F256Uploader F256 Uploader] are unrelated to the "Boot from RAM" DIP switch:
 * The DIP switch alters boot behavior by telling the kernel to search the first 48K of RAM for a pre-loaded kernel binary.
 * Those tools, on the other hand, initiate a new boot using a soft reset signal, and the choice of ''Boot from RAM'' versus ''Boot from flash'' affects the initial memory look-up tables upon boot.
-So those tools' options are also useful for developer convenience, they're just a different behavior affects a different part of the boot process, and is tightly integrated with the act of pushing data over the debug port onto F256K memory.
+So those tools' options are also useful for developer convenience, they just affect a different part of the boot process, and are tightly integrated with the act of pushing data over the debug port onto F256K memory.
 = Memory =

@@ Line 114: / Line 114: @@
 Since the F256K has a larger amount of total memory (up to 768KB) than this address space exposes, programs use and adjust the address space as a "window" to underlying memory needed by the CPU at any given time.
-In other words, programs control what physical memory this address space maps to. They do this through ''memory lookup tables'', or ''MLUT''s for short. Up to four MLUTs can be set up at a time, and programs choose which one is active at any given time.
+In other words, programs control what device memory this address space maps to. They do this through ''memory lookup tables'', or ''MLUT''s for short. Up to four MLUTs can be set up at a time, and programs choose which one is active at any given time.
-Programs choose which bank of CPU address space maps to. Programs can map a bank to any of RAM, flash or expansion memory.
+To ensure that control of MLUTs is always possible, CPU address $0000 is special, and is a memory-mapped register to manipulate MLUTs:
 = Keyboard =

@@ Line 24: / Line 24: @@
 * '''Power Switch''' is a toggle-style switch to turn the unit off and on.
 * '''Reset Button''' reboots the system, with values in RAM persisting. If RAM has been modified using the debug interface, it stays modified.
-* '''Power Jack''' is for plugging in A/C power. Use, for example, a +12V or +9V with 2.5mm Barrel connector.
+* '''Power Jack''' is for plugging in A/C power. Use, for example, a +12V or +9V with 2.5mm barrel connector.
 * '''USB Debug''' is for connection to a debug host computer, debugging F256K as a target, for example using a mini USB to USB A cable.
 * '''PS/2''' can be used for connecting external keyboard and/or mouse.